send_message

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

No annotations are provided, so the description carries the full burden. It usefully discloses two behavioral constraints (allowlist target, env-flag gating) beyond the schema, but says nothing about failure behavior on non-allowlisted chats, rate limits, idempotency, or what the response contains for a write operation.

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 zero filler, and the primary action is front-loaded ahead of the gating prerequisite.

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 write tool with no annotations, no output schema, and 0% parameter coverage, the description covers the critical enablement gate and target restriction but omits what a successful call returns and how errors surface. Adequate to attempt the call, incomplete for confident use.

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 description coverage is 0% — the schema gives types and length bounds but no semantics. The description only gestures at 'chat' via 'allowlisted chat' and does not explain the chatId format (phone number vs JID) or any other meaning for either parameter, so it fails to compensate for the coverage gap.

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 and resource ('Send a text message') plus the scoping qualifier 'to an allowlisted chat'. The word 'text' implicitly separates it from the sibling send_media, though the sibling is never named explicitly.

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?

Discloses a real prerequisite ('Requires WHATSAPP_SENDING_ENABLED=true') and the allowlist constraint, which tells the agent when the call will succeed. However, it never states when to prefer this over send_media or any alternative, leaving routing to inference.

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