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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds the important operational trait that a paid recommendation is never an authorization, plus the requirement to check the live x402 challenge and get user approval. Listing the response fields is partly redundant given an output schema exists, but the payment-authorization disclosure is genuinely beyond structured data.

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?

Three front-loaded sentences with no filler; the core identity leads, followed by outputs and the payment caveat. Enumerating the return fields is slightly redundant with the output schema, but it costs little.

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 output schema means return values need not be explained, and annotations carry the safety profile, so the behavioral story is adequate. However, for a 10-parameter tool with no schema descriptions, the total absence of parameter guidance leaves a real gap in how to actually invoke it correctly.

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 0% across 10 parameters, so the description carries the full burden — and it explains none of them. task, amount, fields, target, network, buyToken/sellToken, maxPriceUsd and the decimals are all undefined in both schema and description, leaving the agent unable to know how to populate them.

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+resource ('task-to-tool router') and immediately scopes it ('Free deterministic', 'not a full catalog'), which cleanly separates it from the sibling signal_layer_catalog. An agent can identify the tool's role without opening the schema.

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 'not a full catalog' framing implies catalog browsing is a different tool, and the description gives concrete operating conditions: it returns an explicit no_match when nothing fits, and may recommend a paid tool without authorizing payment. It stops short of naming signal_layer_catalog as the alternative explicitly, so it is clear context rather than full when/when-not routing.

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