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

With no annotations, the description carries the full burden, but it does disclose genuinely useful behavioral facts: results are deduplicated and categorized, and each call costs $0.002 via x402 on eip155:8453. It omits any statement about input size limits, error behavior, or auth/payment failure handling, which matters for a paid endpoint.

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 short fragments, capability first, with the pricing detail last where it belongs. Slightly clipped style ('Deduplicated, categorized, machine-ready') but nothing that wastes space.

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 two-parameter tool with no output schema, the description should sketch the return shape; it gestures at this ('structured entities', 'categorized') but never states the response format or whether each category is keyed separately. Adequate for invocation, thin on what to expect back.

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 100% and both parameters are documented (the enum values map directly to the entity types named in the description). The description adds no syntax hints, size limits for 'text', or explanation of what 'all' returns, so it does not exceed the schema baseline.

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 (extract) and resource (structured entities from unstructured text) and enumerates the exact entity types returned, so the agent knows precisely what comes out. It does not, however, distinguish itself from nearby siblings such as dev_email_validator or dev_url_parser, which target overlapping entity types.

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 phrase 'Scan unstructured text' implies the input context (freeform text rather than a single field), but there is no explicit when-to-use or when-not-to-use guidance, and no mention of alternatives like dev_email_validator for validating one address. Usage is inferable, not stated.

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