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

Annotations indicate readOnlyHint=false, idempotentHint=false, destructiveHint=false, which suggest a state-changing, non-idempotent, non-destructive operation. The description adds the time limit but does not disclose other behaviors like whether it can edit only recent messages or whether it fails silently if the message is too old. It doesn't contradict annotations, so a 3 is appropriate.

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, concise and front-loaded with the core action. The time limit is placed second, which is useful but not overshadowing. No filler, and every sentence adds value.

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 simple 4-parameter tool with a full schema and annotations that indicate mutation, the description covers the key constraint (time limit). It lacks details on error conditions (e.g., if the edit fails) and doesn't mention what the output schema returns, but the output schema exists and may cover that. Overall, sufficient for an agent to call correctly.

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?

The input schema covers all 4 parameters with descriptions, so the baseline is 3. The description does not add extra semantics beyond the time limit, which is a global constraint rather than parameter-specific. The parameters are well-documented in the schema, so the description doesn't need to compensate.

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 the specific action (edit a WhatsApp message) and the resource (a message you sent), which is clear. It does not explicitly distinguish from wa_send_message or wa_delete_message, but the verb 'edit' is distinct enough given the sibling names.

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 description notes the time limit (within about 20 minutes), which gives important context for when the tool is applicable, but it does not explicitly state when not to use it or mention alternatives like wa_delete_message for deletions. The time constraint is a strong usage signal.

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