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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds the returned field set and identifies the underlying GraphQL query `message`, which is genuinely useful context, but says nothing about permissions, missing-id/not-found behavior, or rate limits.

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 fragments, front-loaded with the resource and immediately followed by the return payload — no wasted words. The telegraphic fragment style is slightly terse but never ambiguous.

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?

For a single-parameter read with no output schema, listing the fields returned and naming the GraphQL query is enough for an agent to call it correctly. Only the absence of not-found/error behavior keeps it from a 5.

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% with a single well-documented message_id parameter, so the baseline is 3. The description only restates 'by id' and adds no format, scoping, or lookup-hint detail beyond the schema.

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 specific verb+resource combination ('One message by id') and enumerates the returned fields (body, from/to, direction, delivery status, error, media), which clearly separates it from sibling reads like get_conversation or list_conversations. It does not explicitly name a sibling, so it falls short of a 5.

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 phrase 'by id' implies that this is a single-record lookup requiring a known message_id, but there is no explicit when-to-use/when-not guidance and no mention of alternatives for discovering message ids (e.g., get_conversation). Usage is only implied.

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