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

With no annotations, the description must carry the burden of behavioral disclosure. It does mention the free tier nature and the lack of payment requirements, which is useful context. However, it does not disclose expected response format, latency, rate limits, or any limitations of the free tier (e.g., response quality) beyond 'try before paying.' This is sufficient for a basic chat tool but lacks depth.

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, with the key information (free tier, no payment) front-loaded. It is concise, with no wasted words. The alternative use case is clearly stated in a short phrase.

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 (2 params, no output schema, no annotations), the description covers the core aspects: what it does, when to use, and the free nature. It does not need to explain return values (no output schema) or complex behavior. Slight deductions for not mentioning any response format expectation, but it's adequate for a minimal chat tool.

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%, with 'prompt' described as 'What to ask.' and 'system' as 'Optional system instruction.' These are quite terse but combined with the schema's description, they are adequate. The description does not add much beyond the schema, but it does set the context that the prompt is for a chat completion. Thus, a baseline 3 is appropriate.

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 is for chat completion on the free tier, naming the specific model (dexl-free). It distinguishes it from paid models and provides a clear use case: 'Use it to try the gateway before paying for a stronger model.' This effectively separates it from the sibling tools, which are about catalogue, payment, models, and pricing.

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 explicitly states when to use this tool: 'No wallet, no account, no payment header. Use it to try the gateway before paying for a stronger model.' This provides a clear rationale for using it over paid alternatives, and implicitly guides against using it for production or when higher quality is needed.

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