List image providers

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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the safety profile is covered. The description adds a meaningful behavioral rule: a provider only appears with configured:true once its key env var is set. This explains a conditional in the output that wouldn't be obvious from the schema alone, going beyond the annotations.

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 exceptionally lean: two sentences. The first states the purpose, the second adds a behavioral condition and a usage tip. Every phrase earns its place, and the most important information (what it lists) is front-loaded. No redundancy, 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 zero-parameter read-only tool with an output schema present, the description covers everything an agent needs: it states the purpose, explains the meaning of configured:true, and tells how to use the returned ids. Return structure and field details are presumably handled by the output schema, so nothing critical 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?

The tool has zero parameters, and the input schema is empty with 100% coverage. Per the rubric, a zero-parameter tool gets a baseline of 4. The description doesn't add parameter-specific semantics because there are none to explain, and it correctly stays silent rather than inventing unnecessary detail.

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 opens with a specific verb and resource: 'List configured image providers' with the additional detail about API key presence. It differentiates cleanly from siblings like list_models (models, not providers) and mutations like add_provider/remove_provider, so an agent can identify this as the pure read-only listing tool.

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?

The description gives a practical downstream use for the result ('Use the returned id values as the prefix in provider:model specs'), which tells the agent how to leverage the output. It doesn't explicitly contrast with sibling tools (e.g., 'when you need models, use list_models'), but the distinctive title and purpose provide clear context without exclusions.

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