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

Annotations already cover safety (readOnly, idempotent, non-destructive), and the description adds real semantics: the full status lifecycle and what each state means, including the 'Android only' caveat on delivered. It does not say what happens for an unknown id, but adds genuine context beyond 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?

One sentence of purpose followed by a compact status glossary; zero waste and the essential fact (single text, by id, with status) 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?

An output schema exists, so return shape need not be explained, and the description still fills the biggest gap — the meaning of each status value. The only omission is behavior on a missing or invalid id.

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?

One parameter at 0% schema description coverage; the phrase 'by id' implies it is the message identifier, which is the obvious reading. That is the minimum needed but nothing more — no format, prefix, or example.

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 retrieve-one resource: 'One text by id, with its status and any error.' The singular 'one text by id' implicitly contrasts with the list/batch siblings, though it never names them.

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 — an agent can infer this is the lookup used to poll a message's status, but there is no explicit guidance on when to use it instead of list_messages, get_batch, or wait_for_reply.

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