[BUG]: Tool invocation fails with Pydantic validation errors 

### 🐞 Bug Summary

Tool invocation fails with Pydantic validation errors when returning resource_link content.

---

### 🧩 Affected Component
Select the area of the project impacted:

- [x] `mcpgateway` - API
- [ ] `mcpgateway` - UI (admin panel)
- [ ] `mcpgateway.wrapper` - stdio wrapper
- [ ] Federation or Transports
- [ ] CLI, Makefiles, or shell scripts
- [ ] Container setup (Docker/Podman/Compose)
- [ ] Other (explain below)

---

### 🔁 Steps to Reproduce

1. resiter a gateway with moody server `https://screening-ai-services.npe.moodys.cloud/mcp`
2. Invoke tool `screenAndWait`

---

### 🤔 Expected Behavior
What should have happened instead?

---

### 📓 Logs / Error Output
Paste any relevant stack traces or logs here.
⚠️ **Do not paste secrets, credentials, or tokens.**

```
2026-01-27T11:21:19 - httpcore.http11 - DEBUG - response_closed.started
2026-01-27T11:21:19 - httpcore.http11 - DEBUG - response_closed.complete
2026-01-27T11:21:19 - httpcore.connection - DEBUG - close.started
2026-01-27T11:21:19 - httpcore.connection - DEBUG - close.complete
2026-01-27T11:21:19 - mcpgateway.services.structured_logger - INFO - [tool_service] MCP tool call completed: screenAndWait
2026-01-27T11:21:19 - mcpgateway.services.structured_logger - ERROR - [tool_service] Tool 'sayujya-mcp-moody-jan-27-v3-screenandwait' invocation failed
2026-01-27T11:21:19 - mcpgateway.transports.streamablehttp_transport - ERROR - Error calling tool 'sayujya-mcp-moody-jan-27-v3-screenandwait': Tool invocation failed: 18 validation errors for CallToolResult
content.0.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.TextContent.text
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.ImageContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.AudioContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('file://moodys-legal-disclaimer/'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.0.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.TextContent.text
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.ImageContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.AudioContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('grid-entities://8...b517-fd4e0e24997f.json'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.2.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
Traceback (most recent call last):
  File "/Users/benjamin/Documents/Projects/ibm_projects/mcpgateway/mcp-context-forge/mcpgateway/services/tool_service.py", line 3202, in invoke_tool
    tool_result = ToolResult(content=filtered_response, structured_content=structured, is_error=is_err, meta=getattr(tool_call_result, "meta", None))
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/benjamin/Documents/Projects/ibm_projects/mcpgateway/mcp-context-forge/.venv/lib/python3.11/site-packages/pydantic/main.py", line 250, in __init__
    validated_self = self.__pydantic_validator__.validate_python(data, self_instance=self)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
pydantic_core._pydantic_core.ValidationError: 18 validation errors for CallToolResult
content.0.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.TextContent.text
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.ImageContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.AudioContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('file://moodys-legal-disclaimer/'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.0.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.TextContent.text
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.ImageContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.AudioContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('grid-entities://8...b517-fd4e0e24997f.json'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.2.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/benjamin/Documents/Projects/ibm_projects/mcpgateway/mcp-context-forge/mcpgateway/transports/streamablehttp_transport.py", line 516, in call_tool
    result = await tool_service.invoke_tool(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/benjamin/Documents/Projects/ibm_projects/mcpgateway/mcp-context-forge/mcpgateway/services/tool_service.py", line 3246, in invoke_tool
    raise ToolInvocationError(f"Tool invocation failed: {error_message}")
mcpgateway.services.tool_service.ToolInvocationError: Tool invocation failed: 18 validation errors for CallToolResult
content.0.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.TextContent.text
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.ImageContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.AudioContent.data
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.0.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('file://moodys-legal-disclaimer/'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.0.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.0.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'Legal Disclaime...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.TextContent.type
  Input should be 'text' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.TextContent.text
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ImageContent.type
  Input should be 'image' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.ImageContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.AudioContent.type
  Input should be 'audio' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.AudioContent.data
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
content.2.ResourceLink.uri
  Input should be a valid string [type=string_type, input_value=AnyUrl('grid-entities://8...b517-fd4e0e24997f.json'), input_type=AnyUrl]
    For further information visit https://errors.pydantic.dev/2.12/v/string_type
content.2.EmbeddedResource.type
  Input should be 'resource' [type=literal_error, input_value='resource_link', input_type=str]
    For further information visit https://errors.pydantic.dev/2.12/v/literal_error
content.2.EmbeddedResource.resource
  Field required [type=missing, input_value={'name': 'gridEntityGroun...'type': 'resource_link'}, input_type=dict]
    For further information visit https://errors.pydantic.dev/2.12/v/missing
2026-01-27T11:21:19 - mcp.server.lowlevel.server - DEBUG - Response sent
2026-01-27T11:21:19 - mcp.server.streamable_http - INFO - Terminating session: None
2026-01-27T11:21:19 - mcpgateway.plugins.auth_pre_check - INFO - [WXO_AUTH] Auth audit: POST /servers/09792051036f4725b5f1e3437fb0d5ce/mcp -> 200 (auth_present=True, client=127.0.0.1)
2026-01-27T11:21:19 - mcpgateway.services.structured_logger - INFO - [http_gateway] Request completed: POST /servers/09792051036f4725b5f1e3437fb0d5ce/mcp - 200
```

---

### 🧠 Environment Info
You can retrieve most of this from the `/version` endpoint.

| Key | Value |
|-----|-------|
| Version or commit | `e.g. v0.9.0 or main@a1b2c3d` |
| Runtime | `e.g. Python 3.11, Gunicorn` |
| Platform / OS | `e.g. Ubuntu 22.04, macOS` |
| Container | `e.g. Docker, Podman, none` |

---

### 🧩 Additional Context (optional)
Add any configuration details, flags, or related issues.


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[BUG]: Tool invocation fails with Pydantic validation errors #2512

🐞 Bug Summary

🧩 Affected Component

🔁 Steps to Reproduce

🤔 Expected Behavior

📓 Logs / Error Output

🧠 Environment Info

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Key	Value
Version or commit	`e.g. v0.9.0 or main@a1b2c3d`
Runtime	`e.g. Python 3.11, Gunicorn`
Platform / OS	`e.g. Ubuntu 22.04, macOS`
Container	`e.g. Docker, Podman, none`

[BUG]: Tool invocation fails with Pydantic validation errors #2512

Description

🐞 Bug Summary

🧩 Affected Component

🔁 Steps to Reproduce

🤔 Expected Behavior

📓 Logs / Error Output

🧠 Environment Info

🧩 Additional Context (optional)

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions