Bug description

Custom bigquery-sql tools that use templateParameters fail on every invocation with:

unable to extract template params: error getting template params missing parameter <name>

The MCP schema (tools/list) correctly advertises template parameters as required input, but when tools/call is received, the template parameter values are silently dropped before reaching Invoke.

Steps to reproduce

1. Define a custom bigquery-sql tool with templateParameters:

kind: tools
name: list_tables
type: bigquery-sql
source: bigquery-source
description: List all tables in a dataset.
statement: |
  SELECT t.table_id, t.row_count
  FROM `{{.dataset}}.__TABLES__` t
  ORDER BY t.row_count DESC
templateParameters:
  - name: dataset
    type: string
    description: "Project-qualified dataset, e.g. project.dataset_name"

2. Start toolbox with --tools-file pointing to the YAML above.
3. Call via MCP JSON-RPC:

{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"list_tables","arguments":{"dataset":"my-project.my_dataset"}}}

4. Observe error: unable to extract template params: error getting template params missing parameter dataset

Root cause

The disconnect is between schema generation and invocation parameter parsing:

Schema generation (bigquerysql.go:78-83) — correct

allParameters, paramManifest, err := parameters.ProcessParameters(cfg.TemplateParameters, cfg.Parameters)
mcpManifest := tools.GetMcpManifest(cfg.Name, cfg.Description, cfg.AuthRequired, allParameters, nil)

allParameters = templateParameters + parameters. The MCP schema correctly advertises all params.

MCP handler (method.go:198) — bug

params, err := parameters.ParseParams(tool.GetParameters(), data, claimsFromAuth)

GetParameters (bigquerysql.go:248-250) — bug

func (t Tool) GetParameters() parameters.Parameters {
    return t.Parameters  // only regular params, excludes templateParameters
}

ParseParams iterates over the parameter definitions list. Since GetParameters() returns only regular Parameters (not AllParams), any template parameter values present in data are silently ignored. The resulting ParamValues is missing the template param entries.

Invoke (bigquerysql.go:117-121) — fails

paramsMap := params.AsMap()  // empty for tools with only templateParameters
newStatement, err := parameters.ResolveTemplateParams(t.TemplateParameters, t.Statement, paramsMap)
// → "missing parameter dataset"

Expected behavior

Template parameter values sent via tools/call should be preserved through ParseParams and available in the paramsMap passed to ResolveTemplateParams.

Suggested fix

GetParameters() should return t.AllParams instead of t.Parameters, so that ParseParams in the MCP handler processes both regular and template parameters. Alternatively, the handler could call ParseParams with all parameters.

Note: this same pattern exists in the REST API handler (api.go:234), and likely affects all tool types that support templateParameters (not just bigquery-sql).

Environment

• Toolbox version: v0.28.0 (commit 81253a0)
• Tool type: bigquery-sql
• Invocation method: MCP stdio (tools/call)
• Also tested via REST API (/api/tool/{name}/invoke) and toolbox invoke CLI — same result