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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so safety is covered without the description. The description adds the useful 'newest first' ordering but says nothing about pagination flow or result volume beyond what the schema states.

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, front-loaded with the verb and ordering, then a compact enumeration of filter modes. No filler and nothing buried.

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 7-parameter list tool with no output schema, the description never indicates what a result looks like or how pagination terminates, leaving the agent to infer that cursor/next_cursor drives paging. Adequate but with gaps for a list endpoint that will usually be paged.

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 only 57%, and the description compensates by explaining filter semantics the schema does not: phone_number is an exact match, q searches name/email/company specifically, and tag/segment_id/list_id are all filters. Only limit/cursor go unmentioned, and those are the two schema entries that are documented.

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?

Names a specific verb and resource plus an ordering guarantee ('newest first'), which an agent can act on directly. It stops short of distinguishing itself from near-siblings such as list_list_contacts or query_audience, so the resource scope is clear but not fully differentiated.

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?

No statement of when to use this versus alternatives — notably list_list_contacts (which also filters by list_id) or query_audience. The filtering sentence describes inputs, not selection criteria, so usage must be inferred.

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