MCP Gemini Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses that the tool sends a message and returns a response that may include text or function call requests, which is useful behavioral context. However, it lacks details on permissions, rate limits, error handling, or whether it's idempotent. For a mutation tool (sending messages likely changes session state), this is a moderate gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core purpose and followed by return value details. Every word earns its place with zero waste, efficiently covering what the tool does and what to expect in response.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given no annotations and no output schema, the description provides basic purpose and return type (text or function call request). However, for a complex tool with 6 parameters (including nested objects) and mutation behavior, it lacks details on error cases, side effects, or response structure. It's minimally adequate but leaves gaps for an agent to use it correctly in edge cases.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all 6 parameters thoroughly. The description doesn't add any parameter-specific semantics beyond implying sessionId is required and message is text-only. This meets the baseline of 3 since the schema does the heavy lifting, but no extra value is provided.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the verb ('sends') and resource ('message to an existing Gemini chat session'), specifying it requires a sessionId. It distinguishes from siblings like gemini_startChat (which creates sessions) and gemini_functionCall (which handles function responses). However, it doesn't explicitly differentiate from gemini_generateContent (which might be for one-off generation without sessions).

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage by mentioning 'existing Gemini chat session' and 'sessionId', suggesting it's for continuing conversations rather than starting new ones. However, it doesn't explicitly state when to use this versus alternatives like gemini_generateContent or gemini_startChat, nor does it mention prerequisites (e.g., needing a session created first).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.