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

With no annotations, the description carries the burden. It transparently discloses that the tool is paid (signal credit or x402 USDC), the cost range, and that uncredentialed calls return a 402 payment envelope with instructions to set X-API-KEY or pay out-of-band. However, it doesn't disclose the response format, success behavior, or any side effects beyond payment. Partial transparency only.

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 a single sentence but packs a lot of information: the market, payment model, authentication method, and out-of-band fallback. It is front-loaded with the purpose but lacks clear structure (e.g., separate sentences for usage and payment). It's not overly verbose, but it could be more organized for readability.

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?

The tool is a paid API call with no output schema, requiring authentication and having an unknown parameter set. The description covers payment and auth but fails to describe what the signal response contains, the meaning of 'category', or any limits. The lack of output format and parameter details makes it incomplete for an agent to effectively use 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?

The input schema has zero properties but allows additionalProperties as strings, and its description points users to the 'instruments' tool for parameter docs. The tool description itself only says 'by category' without specifying what category parameters to pass. It adds no meaningful parameter guidance, leaving the agent to seek external help. The schema coverage is effectively absent for actual params.

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 states 'Futures signal by category' which identifies the market (futures) but lacks a clear verb or resource. It doesn't explicitly say 'Get' or 'Retrieve' a signal, and the 'by category' part is ambiguous without defining categories. The name and phrase distinguish it from other signal_* tools, but purpose remains vague.

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 implicitly indicates it's for futures signals, but no explicit guidance on when to use it versus other signal tools (e.g., signal_perps, signal_equities). It does mention payment requirements, which is a practical consideration, but doesn't state exclusions or alternatives. The context is clear enough from the name but not elaborated.

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