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

Annotations already establish the read-only, idempotent, non-destructive profile, and the description's 'Read' is consistent with that. The description adds useful scoping (body/headers, provider support) but does not disclose behavior such as whether fetching marks the email as read, how attachments are handled, or response shape. Since annotations cover the safety profile, this is acceptable but not exemplary.

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 short sentences, with the core action and scope in the first sentence and workflow placement in the second. There is no filler, repetition, or needless detail; each sentence 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?

The schema carries the complex ID caveats and account-selection rule, while the description supplies workflow placement and a high-level return description ('body/headers') in the absence of an output schema. It could be more complete by explicitly excluding attachments or pointing to email_get_attachment/email_get_thread, but the tool remains callable with the information provided.

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?

Both parameters have 100% schema description coverage, with the email_id description going into depth about provider IDs, IMAP ID instability, and what not to pass. The prose description adds no extra parameter semantics beyond that, so the baseline 3 applies.

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?

States a concrete action ('Read'), the resource ('a specific email'), and the payload scope ('body/headers'), plus supported providers (Gmail, Microsoft/Outlook, IMAP). It is clear enough to be picked over list/resolve tools, but it does not explicitly contrast itself with sibling getters such as email_get_thread or email_get_draft.

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 second sentence is explicit workflow guidance: 'Use after email_list_messages and before a contextual reply or cross-channel decision.' This tells an agent the appropriate position in a multi-step task. It does not, however, name exclusions or alternative tools like email_get_thread for thread-level reads, so it stops short of full when/when-not guidance.

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