read_message

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

No annotations are provided, so the description carries the burden. It explains content transformations (HTML stripped if no plaintext part), truncation behavior, and that only attachment metadata is returned. The explicit warning that email content is untrusted third-party data is especially valuable and goes beyond what annotations would typically provide.

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 compact yet information-dense. Every sentence earns its place: core purpose, return format, truncation behavior, and a security caution. It is front-loaded with the most important identifying 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?

Given no output schema, the description adequately summarizes return contents: decoded headers, plaintext body, and attachment metadata. It also covers truncation and the untrusted-data warning. It could be slightly more explicit about the format parameter's allowed values, but the schema already covers that.

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 adds real value by clarifying that max_body_chars=0 returns the full untruncated body and that the body is plaintext with HTML stripped, which enriches understanding of the message_id and max_body_chars 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 states a highly specific action: read a single message, with details of what it returns (decoded headers, plaintext body, attachment metadata). It differentiates from siblings like read_thread and read_messages by emphasizing 'single message.'

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?

Clear context is provided: this is for a single message, long bodies are truncated by default, and max_body_chars=0 disables truncation. It does not explicitly name alternatives or state when not to use it, but the 'single message' framing makes the intended use obvious.

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