feat(firestore-mongodb): add firestore-execute-mql and firestore-get-…

[pl04351820]

Description

This PR introduces two new Model Context Protocol (MCP) tools for Firestore with MongoDB-compatibility (NL2NoSQL) support:

1. firestore-execute-mql (execute_mql):

   • Executes MongoDB Query Language (MQL) queries and aggregation pipelines directly against Firestore backend instances.
   • Wraps incoming MQL queries into a structuredPipeline with the "iql" stage and read_only: true option, dispatching to Firestore's documents:executePipeline endpoint with routing headers (x-goog-request-params and x-goog-firestore-api-requester).

2. firestore-get-schema (get_schema):

   • Introspects collection structures and data schemas for Firestore collections.
   • Invokes the "get_schema" structured pipeline stage with mongodb semantics ({ "collection": "<name>", "semantics": "mongodb" }), flattening nested fields into dot-separated paths with their data types.
   • Includes graceful fallback document sampling when pipeline stages are unavailable.

Reference: go/fs-nl2nosql-mcp-tools

Summary of Changes:

• internal/sources/firestore/firestore.go: Added ExecutePipeline and GetSchema methods with structured pipeline payloads and header context.
• internal/tools/firestoremongodb/: Added firestore-execute-mql and firestore-get-schema tool implementations with parameters, annotations, and input validation.
• Unit Tests: Added test suites covering YAML unmarshaling, mock tool invocations, destructive/read-only annotations, schema extraction, and type resolution (firestoreexecutemql_test.go, firestoregetschema_test.go, firestore_internal_test.go).
• cmd/internal/imports.go: Registered new tool packages.
• docs/en/integrations/firestore/tools/: Added documentation pages following Hugo documentation standards.

PR Checklist

• Make sure you reviewed CONTRIBUTING.md
• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea.
• Ensure you have manually reviewed the entire diff before requesting a review
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)
• Make sure to add ! if this involve a breaking change

🛠️ Fixes #<issue_number_goes_here>

[gemini-code-assist]

Code Review

This pull request introduces MongoDB Query Language (MQL) query execution and schema retrieval capabilities for Firestore by adding the firestore-execute-mql and firestore-get-schema tools, along with their respective documentation and unit tests. Feedback on the changes includes improving the robustness of the Firestore source implementation by using json.Marshal instead of fmt.Sprintf for query construction, capping the sampleSize to prevent potential memory issues, and including the response body in API error messages. Additionally, the reviewer noted that the firestore-execute-mql tool should default to read-only annotations rather than destructive annotations, which also requires updating the corresponding unit tests.