gmail_get_message

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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint). The description adds that it returns the full message including body text, which is useful behavioral info not in annotations. No contradictions.

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 only two sentences, front-loading the core purpose. Every word is functional—no filler. It's as concise as possible while still adding meaning.

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 single-message retrieval tool, the description covers the essential purpose and parameter source. An output schema exists, so return structure is handled. It doesn't discuss edge cases like missing IDs, but that's likely acceptable given the tool's simplicity and the presence of sibling tools for related operations.

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%, so the description must compensate. It does explain the source of message_id ('from gmail_search'), giving semantic context. However, it doesn't mention format, constraints, or potential errors, leaving some ambiguity for the single parameter.

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 states a specific verb and resource: 'One message in full, including its body text.' This clearly distinguishes it from siblings like gmail_get_thread (which returns an entire thread) and gmail_get_draft (for drafts). The purpose is unambiguous.

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?

It provides context by specifying that message_id comes from gmail_search, implying a typical workflow. However, it doesn't explicitly mention when to prefer this over gmail_get_thread or list similar exclusions. The guidance is sufficient for an agent to infer usage.

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