list_contacts

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

Annotations only declare readOnlyHint=true. The description adds genuinely non-derivable behavioral facts: results are returned oldest first, and pagination is cursor-based. It stops short of 5 because it says nothing about auth requirements, rate limits, or result volume.

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 with zero filler; the core behavior and ordering are front-loaded and the filter hint follows. Nothing is wasted.

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 list tool with no output schema and full parameter coverage, the description covers scope, sort order, pagination style, and filtering. The only gap is that no return-shape guidance is given, though with no output schema that is a minor omission.

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 all four parameters (after, before, limit, segment_id) are already documented, including forward/backward paging semantics and the mutual exclusion of after/before. The description's segment_id sentence restates the schema description, so the baseline 3 applies.

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 ('List contacts of the team') and adds scope (team-wide) and ordering (oldest first), which cleanly separates it from get_contact and list_suppressions. It does not explicitly name or differentiate from any sibling, so it falls short of a 5.

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?

'Pass segment_id to list only that segment's members' hints at the optional filter, but there is no when-to-use vs when-not guidance and no named alternative (e.g., search or get_contact for a single record). Usage is implied rather than stated.

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