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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is not the sole carrier. The access paragraph does add genuinely useful operational context beyond annotations: cost of 0.001 USDC via x402, the PAYMENT-SIGNATURE header, and that x402 clients auto-pay while API-key clients pay nothing. However, it says nothing about what a validation outcome looks like or whether invalid parameters throw or return a result.

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 core purpose is front-loaded in one short sentence, and the bracketed access note is clearly demarcated rather than interleaved. The access note is proportionally long for a two-parameter tool, but it is structured and scannable rather than wasteful.

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?

This tool takes a nested free-form object and has no output schema, so the description carries the burden of explaining both the shape of 'parameters' and what validation returns. Neither is addressed. For a nested-object tool whose entire job is checking an opaque payload, the definition is under-specified.

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 coverage is only 50%, and the undocumented parameter is the important one: a free-form 'parameters' object with default {} and no description anywhere. The description never explains what keys that object expects or how they relate to a signal's parameter set. Only 'signal_name' is documented, and only in the schema.

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?

States a specific verb and resource: validate the parameters of a signal. An agent can immediately tell this is a pre-flight check rather than an evaluation (evaluate_signal) or a retrieval (get_signal). It does not explicitly name those siblings or draw the boundary, which keeps it out of 5 territory.

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 only second sentence concerns payment and auth mechanics, not when to call the tool. There is no guidance on whether to validate before evaluate_signal, what to do on failure, or how this differs from query_signal_behavior. Usage must be inferred entirely from the name.

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