Find Contacts

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

The annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the scope of results (all vs. filtered by JID) but does not disclose additional behavioral nuances like pagination, ordering, or partial field returns. With annotations bearing the safety burden, the description adds some but not rich behavioral context.

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 a single, focused sentence and a half: 'Search WhatsApp contacts. Returns all contacts if no filter is provided, or a specific contact by JID.' Every word earns its place, with no filler or redundant phrasing.

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?

The tool is simple: one optional parameter, no output schema, and annotations covering safety. The description explains both modes and the parameter's semantics, fully covering the tool's behavior. No additional context is necessary for an agent to use 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 description coverage is 100%, as the only parameter filter_id is thoroughly documented with an example JID and instruction to omit for all contacts. The description does not add any information beyond what the schema already provides, so it meets the baseline but does not enhance understanding.

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 clearly states the tool's function: 'Search WhatsApp contacts.' It further specifies the scope (all contacts vs. a specific contact by JID), which distinguishes it from sibling tools like send_contact that generate contact cards rather than search the contact list. The verb 'search' and resource 'WhatsApp contacts' are specific and unambiguous.

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 provides clear context for when to use the tool: 'Returns all contacts if no filter is provided, or a specific contact by JID.' This implies the primary use cases. However, it does not explicitly mention exclusions or alternatives, such as 'use fetch_profile for profile details' or 'do not use for sending contacts,' so it does not reach the level of fully exploring when not to use it.

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