list_providers

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

There are no annotations, so the description carries full burden. It mentions that providers without keys will error when called, which is a useful behavioral warning. However, it doesn't disclose potential side effects (though listing is read-only, it could be mistaken), nor does it explain implications of configuration status, but the warning is a positive.

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 two sentences, extremely concise, and front-loaded with the core action (list all providers) and output details. Every sentence provides value: the second clarifies error behavior. No redundancy or fluff.

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?

Given the tool's simplicity (no parameters, no output schema, no annotations), the description covers key aspects: what it lists, the error condition. It lacks explicit mention of the exact return format or whether it includes provider IDs, but for a list tool, this is largely sufficient. A minor gap is not specifying if it returns configuration status as structured data or human-readable text.

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, so there are no parameter semantics to explain. The description focuses on the output content (default models, configuration status), which is sufficient. With no parameters, a baseline of 4 is appropriate as the description adds meaning about the result.

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 states the tool lists all registered vision model providers, including their default models and configuration status. It distinguishes itself from sibling tools (analyze/describe/ocr) which are image-related operations, though it doesn't explicitly compare.

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 doesn't explicitly state when to use this tool vs alternatives, but the purpose is clear enough that an agent would know it's for listing providers, not image analysis. It conveys usage context implicitly by listing what it returns, but no explicit exclusions or alternative tool references.

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