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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses key behavioral traits: the specific model (Claude Haiku), per-token billing, and the prepaid session requirement. It does not contradict the annotations, and these details add meaningful context for an agent.

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 and front-loaded with the core purpose. Every word adds value: 'OpenAI-style' defines the API shape, 'Claude Haiku' specifies the model, and billing/prepaid are key operational constraints.

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 3-parameter tool with annotations and no output schema, the description covers the essential purpose, billing, and prerequisite. It does not describe the return format, but 'OpenAI-style chat completion' implies a standard response structure. A small gap remains, but the description is largely complete for an agent to select and invoke the 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 only 33%, but the description says 'OpenAI-style', which conveys standard semantics for messages, max_tokens, and temperature to an agent familiar with OpenAI APIs. It does not explicitly explain max_tokens or temperature, so it only partially compensates for the low schema coverage.

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's function with a specific verb and resource: 'OpenAI-style chat completion (Claude Haiku)'. This distinguishes it from siblings like catalog, crypto_price, funding_rates, and random, which are unrelated.

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 provides clear context by specifying the billing model ('billed per token off-chain') and a prerequisite ('Needs a prepaid session'). It implies use for chat completion but does not explicitly mention alternatives or exclusions, so it stops short of a 5.

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