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

Annotations already declare readOnlyHint=true, so the safe-read profile is covered. The description adds the underlying HTTP endpoint (GET /v1/whatsapp/messages/{message_id}), which is mildly useful context, but nothing about error cases for missing ids or what the payload contains.

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 compact sentences, front-loaded with the action and resource, with the endpoint path as supplementary detail. No wasted words.

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 trivial one-parameter read tool with no output schema, the description covers what it does and the identifier used. Only minor gaps remain (no note on behavior for unknown ids, no pointer to the list tool for discovering ids).

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% for the single message_id parameter, so the schema already documents its meaning. The description adds no format, syntax, or sourcing detail beyond what the schema provides, 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 specific verb (fetch) and resource (a single WhatsApp message) and scopes it to lookup by id, which implicitly separates it from the sibling list_whatsapp_messages. It does not name that sibling explicitly, but the 'single ... by id' phrasing is enough to distinguish single-fetch from list.

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?

'By id' implies the prerequisite of already having a message id, but there is no explicit when-to-use, when-not-to-use, or named alternative (e.g., list_whatsapp_messages for discovery). Usage context is inferable rather than stated.

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