Gmail MCP Server

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

With no annotations provided, the description carries full burden and does well: it discloses authentication requirements, prerequisites for obtaining email IDs, and the comprehensive nature of the returned context. It doesn't mention rate limits, error conditions, or performance characteristics, but covers essential behavioral aspects for a context-gathering tool.

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?

Well-structured with clear sections (description, prerequisites, args, returns, example usage). The description is appropriately sized for a complex tool, though the example usage section is somewhat verbose. Every sentence adds value, with no redundant information.

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?

For a complex tool with no annotations and no output schema, the description provides substantial context: purpose, prerequisites, parameter explanation, detailed return value structure, and usage workflow. The main gap is lack of error handling information, but overall it's quite complete for agent guidance.

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 0%, but the description compensates well: it explains that email_id is 'The ID of the email to reply to' and provides guidance on obtaining it from list_emails() or search_emails(). While it doesn't specify format constraints (like expected string pattern), it adds meaningful context beyond the bare schema.

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 tool's purpose: 'Prepare a context-rich reply to an email' with specific details about what context is gathered (original email, thread history, sender information, etc.). It distinguishes from siblings like 'send_email_reply' (which actually sends) and 'get_email' (which retrieves single emails without comprehensive context).

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?

Explicit guidance is provided: 'Prerequisites' section states authentication requirements and how to obtain email IDs from list_emails() or search_emails(). The 'Example usage' section gives a step-by-step workflow, clearly indicating when to use this tool versus alternatives like list_emails() for ID acquisition and send_email_reply() for actual sending.

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