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

Annotations already establish readOnlyHint, idempotentHint, and non-destructive behavior, lowering the bar. The description adds useful behavioral context by stating that it retrieves body/headers across multiple providers, and the schema further clarifies IMAP ID mutability. This goes beyond simply repeating the annotations.

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 two sentences with no filler: the first sentence states the core operation and scope, the second provides necessary workflow positioning. Every sentence earns its place and key information is front-loaded.

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?

With no output schema, the description's mention of 'body/headers' gives an agent a reasonable idea of return content. Combined with rich parameter schema and annotations covering safety and idempotency, the definition is sufficiently complete for correct invocation, though it could add more detail on response format or error cases.

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 100%, and the input schema already provides extensive detail on email_id provenance, IMAP ID behavior, and account_id disambiguation rules. The tool description itself adds little parameter meaning beyond the schema, so the baseline score of 3 is appropriate.

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 action and resource: 'Read a specific email including body/headers' and names the provider scope 'Gmail, Microsoft/Outlook or IMAP.' It is distinguishable from list-oriented siblings like email_list_messages, though it does not explicitly contrast itself with closely related email_get_thread.

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 clear pipeline context: 'Use after email_list_messages and before a contextual reply or cross-channel decision.' This tells the agent where the tool fits in a workflow, but it does not give when-not-to-use guidance or direct comparisons with alternatives like email_get_thread or email_resolve_message.

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