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

readOnlyHint=true already declares the safe-read profile, so the bar is lower. The description adds that results are paginated ('returns a page of people') and that filters are optional, plus the backing REST endpoint. It does not cover pagination limits (which the schema does) or auth/rate-limit behavior, so it is useful but not rich.

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 short, front-loaded sentences with no padding. The REST endpoint line ('POST /people/search') is marginally low-value for an agent and is the only sentence that does not clearly earn 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 13-parameter read tool with full schema coverage and a readOnly annotation, the essentials are present, and the pagination hint partially compensates for the absent output schema. It is adequate but thin: no guidance on result shape beyond 'a page of people' and no routing context against the other search tools.

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% — every one of the 13 parameters is documented in the schema with defaults, ranges and match semantics. The description only restates that filters are optional, adding nothing the schema lacks; baseline 3 is correct.

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+resource ('Search/list people (contacts)') and adds scope detail — all filters optional, returns a page. An agent can distinguish this from copper_get_person (single-record fetch) and copper_search_companies (different resource). It stops short of explicitly naming the alternate tool it is not, so it does not reach 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?

The only usage signal is 'All filters optional', which implies a bare call acts as list-all. There is no statement of when to prefer this over copper_get_person (known ID) or how it relates to the sibling search tools, leaving the agent to infer the routing.

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