find_contact_by_phone

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

With no annotations, the description carries full burden. It discloses that numbers are normalized (ignoring spaces, dashes, formatting) and matched exactly across all phone fields. This is good, but could mention that it's a read-only operation. No contradictions.

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?

Two short sentences plus examples. Every sentence is informative and earns its place. Front-loaded with usage guidance and examples. No wasted words.

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 simplicity (3 params, no output schema), the description covers purpose, usage, behavior, and parameter hints. No gaps for an AI agent to misinterpret.

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%, so baseline is 3. The description adds value by explaining normalization behavior for the phone parameter, which is not in the schema description. It also provides usage context for top and scanLimit (increase on larger phonebooks). This exceeds the minimum.

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 purpose: finding who owns a phone number. It provides specific example queries, making it easy for an AI agent to match user intent. It also distinguishes from sibling tools like search_contacts which would be used for broader searches.

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?

Explicitly tells when to use the tool: 'Use this when the user provides a specific phone number and wants to know who it belongs to'. It gives concrete examples and implicitly suggests alternatives (e.g., search_contacts for general searches).

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