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

No annotations are provided, so the description carries the full burden, and it discloses nothing: no side effects, no indication of what gets sent or opened, no auth requirements, no reversibility. An agent has no idea whether this mutates state or is a safe read.

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?

It is short, but this is under-specification rather than conciseness — the single fragment carries almost no information and does not front-load a usable verb-resource pairing.

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 tool with an undocumented parameter, no annotations, and no output schema, the description is completely inadequate. An agent cannot determine what calling it does or what a valid phone_number looks like.

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 single phone_number parameter has 0% schema description coverage, and the description adds nothing about expected format (E.164, country code, digits only) or what the number identifies. The description 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?

The description 'WhatsApp Web: contact about' essentially restates the tool name and adds only a platform hint. It does not state what action is performed on the contact — whether it opens a chat, initiates a conversation, or something else — so an agent cannot confidently distinguish it from siblings like converse, send_text, or check_number.

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?

There is no guidance on when to use this tool versus the many overlapping siblings (converse, send_text, reply_message, check_number). No prerequisites, no exclusions, no context of any kind.

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