get_contacts

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

Annotations already indicate readOnlyHint=true. Description adds context that results are frequency-derived from recent email history, not a contacts address book, and notes the dependency on the mailbox index. No contradiction with 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?

Three sentences and a note, all concise and front-loaded with the main purpose. No unnecessary words, good structure.

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 low complexity (1 optional parameter, no output schema), the description covers purpose, usage, behavioral notes, and prerequisite. It does not mention return format, but it is adequate for the tool.

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% with a single 'limit' parameter described. The description does not add any additional meaning beyond the schema, so baseline score of 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?

The description clearly states that the tool returns frequently contacted email addresses ranked by interaction volume. It distinguishes from a contacts address book, but does not explicitly differentiate from the sibling tool 'top_senders', though it is specific enough.

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 clear use cases: identify key correspondents or pre-populate recipient lists. Also includes a prerequisite (local mailbox index populated) and suggests calling sync_emails if needed. Does not list alternatives or exclusions explicitly.

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