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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful context beyond those hints: the tool requires zero input and explains the consequence of using an invalid filter value elsewhere. This aligns with the closed-world annotation and gives an agent actionable behavioral expectations.

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?

The description is compact and efficient. It front-loads the core value, lists relevant filter categories, and adds usage guidance in a single extra sentence. Every sentence earns its place with no redundancy.

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-input lookup tool with rich annotations, the description provides enough information to call it correctly: what it returns, that no input is needed, and when to use it. It does not specify the exact output structure, but that is a minor gap given how simple and focused the tool is.

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 no parameters, and schema coverage is trivially complete. The description reinforces this with 'Zero input.' No parameter documentation is needed, so the baseline of 4 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?

The description clearly identifies the resource (accepted filter values) and the main point: this tool returns the full vocabulary of filters. It lacks an explicit verb like 'list' or 'retrieve,' and it does not explicitly distinguish itself from siblings, but the resource is unique enough that an agent can infer its purpose.

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 explicitly says to call the tool when unsure about a filter valueches and warns that an out-of-vocabulary value errors. There is no mention of when not to use it or alternatives, but no sibling performs the same function, so the guidance is clear and sufficient.

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