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

Beyond annotations (readOnlyHint=false, destructiveHint=false), the description states it is a write operation, explains the two-step confirm/preview behavior, and warns about the unofficial Wacli client and potential ToS restrictions. This is valuable behavioral context not captured in structured data.

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?

Every sentence earns its place: action, mandatory provenance constraint, file path constraint, write/confirm workflow, and risk warning. Information is front-loaded and there is no redundancy or filler.

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?

Output schema exists so return values are covered. The description covers input provenance, path requirements, confirmation workflow, and risk profile. For a write operation with an unofficial client, this is complete enough for an agent to call it 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?

Schema coverage is 100%, but the description adds meaning by reinforcing that chat_id must come from a prior call, file_path must be absolute, and confirm controls the send. The 'never fabricate IDs' warning goes beyond schema text.

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?

Description opens with 'Sends a file attachment to a WhatsApp chat' — a specific verb, resource, and scope. It clearly differentiates from siblings like whatsapp_send_message (text) and whatsapp_send_poll (poll) by focusing on file attachments.

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?

Provides explicit procedural guidance: chat_id must come from whatsapp_list_chats, IDs must never be fabricated, and confirm=false returns a preview before confirm=true sends. It lacks explicit exclusions or alternatives, but the context is clear and actionable.

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