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

Annotations already declare readOnlyHint and non-destructive, so safety is covered; the description adds real value with the soft-delete exclusion ("Trashed contacts are left out") and the exact projected return fields. It stops short of stating result cap behavior or whether matches are ranked, which an agent planning pagination would want.

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 sentences with zero filler: purpose and searchable fields first, then the trashed exclusion, then the return shape and APIv4 provenance. Nothing is redundant.

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 search with 4 well-documented parameters and no output schema, the description supplies the entity subtypes, the exclusion rule, and the returned fields, which is essentially everything needed to call it correctly. Only routing versus civicrm_get_contact and pagination hints are absent.

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 limit, offset, query and contact_type are already fully documented, including offset chaining via next_offset. The description only restates query semantics and the optionality of contact_type, adding little beyond the schema. 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 ("Find contacts") plus the searchable fields (name, e-mail, phone) and the entity subtypes (people, organizations, households). It does not explicitly distinguish itself from the sibling civicrm_get_contact (ID lookup) or civicrm_query, so an agent still has to infer which to pick.

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?

Usage is implied by "by a word in their name, e-mail address or phone number" and by noting that an empty query lists contacts, but there is no explicit when-to-use/when-not or routing to civicrm_get_contact for known IDs. The trashed exclusion is a scope note rather than guidance.

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