get_message

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

With no annotations supplied, the description carries the full burden and delivers real behavioral detail: plain text is the default format, HTML bodies are sanitized and truncated, and untrusted content is demarcated in <untrusted_email_content> markers with a summary/sender/recipient fields under an "untrusted" key plus an explicit prompt-injection warning. It does not cover error cases (e.g., nonexistent id) or whether truncation is signalled in the response, which keeps it below a 5.

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?

Two sentences, front-loaded with what is returned and followed by the security-relevant handling of that content. No filler, and the safety instruction is placed where an agent will read it before acting on the body.

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?

There is no output schema, so the description must and does describe the return shape (headers, recipients, body, and the untrusted key structure) and the sanitization/truncation behavior. Gaps remain around error behavior and whether a truncation indicator is returned, but for a three-parameter read tool this is close to complete.

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 67% and the undocumented "id" is self-evident from the tool name and required field. The description adds genuine meaning beyond the schema for the other two: it states text is the default format and that html is sanitized and truncated, which explains the real consequences of choosing that enum value rather than just restating it.

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 uses a specific verb and resource ("Get one message") and enumerates what is returned (headers, recipients, body), which implicitly separates it from the plural siblings list_messages and search_messages. It stops short of naming those siblings explicitly, so the differentiation is inferable rather than stated.

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?

Usage is only implied: the required "id" parameter signals this is for retrieving a single known message, whereas list/search siblings would be used for discovery. There is no explicit "use this when... / use X instead when..." guidance, and no mention of prerequisites such as being logged in.

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