send_message

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

Annotations indicate readOnlyHint=false and destructiveHint=false, and the description adds meaningful behavioral context: the message appears as a fresh message, is stored locally, is reversible, and returns a specific JSON. This enhances understanding beyond the annotations.

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 concise (two sentences plus return format), front-loaded with the core purpose, and efficiently includes alternatives, reversibility, and return structure without any redundant wording.

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?

Given the tool's moderate complexity (3 parameters, no output schema), the description fully covers the effect, behavior, return format, and links to sibling tools. No gaps remain.

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 100% with clear parameter descriptions. The tool description reinforces the recipient format and the mark_chat_read effect, but does not add substantial new meaning beyond the schema. Baseline 3 is appropriate.

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 uses a specific verb ('Send') and resource ('new WhatsApp text message'), and clearly distinguishes this tool from siblings like send_reply and send_reaction by stating when to use those alternatives. It also explains the effect (fresh message, local cache storage).

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 explicitly directs the agent to use send_reply for quoting, send_reaction for emoji acknowledgement, and mentions reversibility via delete_message or edit_message. This provides clear when-to-use guidance, though it does not explicitly state when not to use this tool (e.g., for replies).

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