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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds real value beyond that: the exact return envelope ({ count, next_skip, items }), the pagination protocol (pass next_skip as skip), and the underlying endpoint. It stops short of noting rate limits or default ordering.

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 very dense sentences with no filler, and the return shape is front-loaded right after the resource definition. The opening is a noun fragment rather than a verb phrase, which slightly weakens the front-loading, but nothing is wasted.

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 takes on the job of explaining the return envelope and pagination, and it does so correctly. For a six-parameter, zero-required list tool this is close to sufficient; only a note on default sort/paging behaviour and query error handling is missing.

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 every parameter including id, skip, sort, limit, query and filters is already documented in the schema. The description restates the query ('MongoDB-style') and paging ('pass next_skip as skip') but adds no syntax or edge-case detail beyond what the schema already carries, which is the baseline 3 case.

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?

The description names the resource ('custom field definitions') and enumerates the salient content (label, type, which records they apply to), plus the endpoint GET /custom-fields. The listing verb is only implied by the title and the paginated return shape, but an agent can tell this apart from sibling list tools by resource name alone.

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?

It hints at variants ('Pass id to read one record') and explains paging and filtering, which is useful selection guidance within the tool. However, it never says when an agent should reach for this tool versus something else, and no prerequisites or exclusions are stated.

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