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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered; the description adds the underlying endpoint (GET /custom_fields.json) and the return shape, which is useful context but not essential behavior. Pagination behavior (next_page tokens via page_token/offset) is left entirely to the schema.

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 compact sentences, front-loaded with purpose and return contents before the usage hint and endpoint. The middle clause is dense but every clause earns its place; no filler.

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 10-parameter, no-output-schema list tool, the description covers purpose, returned fields, and how results chain into siblings — enough to call it correctly. Pagination semantics and default field set are only implied by the schema, so it falls just short of 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% with three enums documented inline, so the schema carries all parameter meaning. The description adds nothing about limit, order, deleted, field_type, or parent_type, 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?

Specific verb (list) plus resource (the firm's custom fields), plus explicit scope (matters or contacts) and the concrete payload (name, type, required, picklist option id + text). An agent can distinguish this from clio_list_matters or clio_list_contacts without opening any schema.

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 states the downstream use: the ids feed clio_list_matters / clio_list_contacts filters and decode values returned by clio_get_matter / clio_get_contact. That is real routing guidance, though it never says when NOT to call it or what alternative to prefer.

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