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

Annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds useful behavioral context beyond that: it returns confidence/risk/recommendation and requires a Loqate API key. It slightly oversimplifies by saying a key is required when the schema notes it can be server-configured or supplied via bearer token, but this is not a contradiction of the annotations.

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 sentences carry the entire message with no filler. The purpose is front-loaded, the return values are stated compactly, and the API key requirement is placed at the end as an actionable note. Every sentence earns its place.

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 read-only verification tool, the description covers the core purpose, output summary, and authentication requirement. There is no output schema, so mentioning the return fields is helpful. It could be more complete by noting error behavior or the conditional nature of the API key, but the schema already covers parameter-level details.

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 each parameter is already documented. The description reinforces that the API key goes in the 'key' field, but it adds no substantial meaning beyond the schema and does not elaborate on the policy parameter or result interpretation.

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 states a specific action ('Verify') applied to a specific resource ('an email address') and names the provider ('Loqate'). It also previews the result ('confidence, risk level, and accept/review/reject recommendation'), which makes the tool's purpose unmistakable and distinguishes it from sibling verification tools like verify_address, verify_phone, and verify_contact.

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 clearly establishes that this tool is for verifying email addresses, so the usage context is clear. However, it does not explicitly call out when not to use it or direct the agent to sibling tools such as verify_address or verify_phone, so it stops short of full alternative-selection guidance.

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