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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real value by disclosing the shape of the response (custom fields included, pick-list options exposed), which matters because there is no output schema. It does not mention that the 'action' parameter changes which fields are relevant, a minor gap.

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 tight clauses: what is returned, when to use it, and the underlying APIv4 call. Front-loaded and waste-free, though the final 'APIv4 <Entity>.getFields' fragment is more implementation trivia than agent-relevant guidance.

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?

With no output schema, the description carries the burden of explaining return content and does so adequately, including the custom-field caveat. It falls slightly short on how the action parameter changes the field set, but for a read-only introspection helper it is otherwise complete.

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%, so both 'field' and 'action' are already documented in structured form, establishing a baseline of 3. The description only implies the 'entity' parameter through its prose and adds nothing about restricting to a single field or how 'action' affects results.

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 — describing the fields of one CiviCRM entity — and enumerates exactly what metadata is returned (name, label, data type, required, pick-list options). No sibling tool does metadata introspection, and the description makes that role unmistakable.

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?

Explicitly tells the agent when to call it: to find the right field names for civicrm_query and the correct option names for filters and write tools. That routes the agent to the correct sibling dependency rather than guessing field names.

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