find_contact

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

No annotations exist, so the description carries full burden. It mentions case-insensitive substring matching and the return of mids, but does not specify the full return structure (e.g., array format, other fields), pagination, or error handling.

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?

Extremely concise with two sentences. Front-loads the core action and follows with key constraints. No extraneous text.

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 simple tool with one parameter and no output schema, the description sufficiently covers behavior and return intent. Lacks explicit handling of edge cases (e.g., no match) but is adequate for basic 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?

The sole parameter 'name' is fully described in the input schema (100% coverage). The description echoes the schema's details but adds no new information beyond reinforcing 'case-insensitive substring'.

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?

Clearly states the tool finds LINE friends by matching a substring on display name, case-insensitively. Distinguishes from siblings like 'list_contacts' and 'search_messages' by specifying the matching logic and return value.

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 context that this is a raw lookup without ranking or fuzzy scoring, guiding the agent to use it for exact substring matching. Also indicates it returns mids for send_message, implying its role in a workflow.

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