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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds that it returns candidates with match reasons, but it does not add auth needs, rate limits, pagination behavior, or what happens when no candidates are found.

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 efficient sentences with no wasted wording. The usage condition is front-loaded, though the core purpose verb arrives after it rather than in the first clause.

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 read-only lookup with rich annotations and an output schema, the description is nearly adequate. Its main gap is that it does not differentiate this tool from contacts.duplicates.find, which is important context for correct tool selection.

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%, so the schema already documents all five parameters, even if tersely. The description adds no parameter-level meaning such as which fields drive matching or how limit interacts with candidate ordering, so 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?

States a specific verb and resource: checking whether a person already exists before creating a contact. It is clear what the tool does, but it does not distinguish itself from the sibling tool contacts.duplicates.find, so an agent still lacks a clean basis for choosing between the two.

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 says when to use it: before creating a new contact. However, it does not name alternatives such as contacts.duplicates.find or state when not to use this tool, so the sibling ambiguity remains unresolved.

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