email_contacts

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

No annotations are provided, so the description bears full responsibility. It states 'extract contacts from recent emails' but does not clarify which folders are scanned (inbox only?), what constitutes a contact, or edge cases like deleted emails. It is minimally adequate.

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, no wasted words. The first sentence states the core functionality, the second gives a practical use case. Perfectly concise and front-loaded.

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 has three optional parameters and no output schema. The description does not mention the return format (e.g., array of email strings) or any limitations like handling of duplicate addresses (addressed by param but not described). It is somewhat incomplete for a tool that produces a list.

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?

All three parameters have descriptions in the schema (100% coverage), so baseline is 3. The description adds no extra meaning beyond 'recent emails' which loosely ties to the 'days' parameter. No additional syntactic or semantic guidance is provided.

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 verb ('extract') and resource ('contacts from recent emails'), and the use case ('building contact lists for campaigns'). No other sibling tool explicitly handles contact extraction, so it distinguishes well.

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 implies usage for campaigns but does not specify when to avoid this tool, nor does it mention alternatives like email_search or email_read. It lacks explicit guidance on prerequisites or exclusion criteria.

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