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

Annotations cover the safety profile (readOnlyHint=true), and the description adds real value on top: it discloses the returned attributes (id, name, type, allowed values) and the underlying API endpoint. It does not discuss pagination or whether the list is exhaustive, so it is not fully 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 sentences with zero filler; the resource and its returned shape come first, then the actionable usage note, then the API reference. Everything is front-loaded and earns 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 zero-param reference lookup with no output schema, the description covers what is returned (id, name, type, allowed values) and how to consume it, which is most of what an agent needs. The only unaddressed details are pagination and list completeness.

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?

There are zero parameters and the schema is trivially complete, so the baseline is 4. The description correctly adds no parameter commentary, since there is nothing to document.

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 ('List') and a precise, unique resource ('the church's custom person fields') with the returned attributes enumerated. No sibling covers custom fields, so an agent can select it without ambiguity against the many list_* and get_* siblings.

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?

Gives concrete downstream usage: take the id and use it as 'custom_<id>' in fields / search, which explains why and when an agent should call this. It stops short of naming an explicit alternative or a when-not-to-use condition, but the context is clear.

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