Get message

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

The annotations already set readOnlyHint=true, so the description's addition of what the tool returns (headers, bodies, attachment metadata) adds value but doesn't disclose deeper behavioral traits like pagination, size limits, or performance. The description is adequate but not rich.

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 a single, efficient sentence that front-loads the purpose ('Fetch a full message') and adds essential distinctions. Every word earns its place.

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 simple read tool with 2 parameters and no output schema, the description is fairly complete. It clarifies the tool's scope and relation to a sibling. Missing info on response format or restrictions, but still sufficient for basic selection.

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 coverage is 100%, so the baseline is 3. The description does not add meaning beyond the schema; it merely restates that gmMsgId comes from search_messages or get_message, which is already in the parameter descriptions. No extra semantics for parameters.

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 specifies 'Fetch a full message: headers, plain-text and HTML bodies, and attachment metadata' and explicitly distinguishes from the sibling tool 'get_attachment' by directing users there for byte content. This makes the tool's purpose very clear and specific.

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 provides clear context on what the tool returns and points to an alternative for attachment bytes. However, it does not explicitly state when to use this tool over other siblings like search_messages, which could be implied. Still, it offers good differentiation from a key sibling.

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