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

With no annotations, the description carries the full burden. It usefully discloses that this is a paid call ($0.001 USDC on eip155:8453 via x402), which is real behavioral context an agent needs before invoking. It does not disclose what happens on malformed input or how query parameters with duplicates/encoding are handled, so the disclosure is partial.

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?

Two tight sentences with the core purpose front-loaded and no filler. The pricing clause is appended after an em-dash and reads as an unrelated tag rather than integrated information, which slightly disrupts the flow but does not waste 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?

There is no output schema, so the description correctly enumerates the returned components, which is exactly what an agent needs to know the shape of the result. It omits error behavior for invalid URLs and any note about query-string edge cases, leaving a small gap for a tool of this simplicity.

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?

There is a single parameter with 100% schema description coverage, so the baseline is 3. The schema description is only 'URL', and the description adds nothing about accepted formats (absolute vs relative, scheme required, encoding) beyond restating that a URL is parsed.

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 ('Parse') and resource ('a URL') and enumerates the exact output components (protocol, hostname, port, path segments, query params as a clean object, hash, credentials). This enumeration implicitly separates it from siblings like dev_url_encoder, dev_url_reader, and live_url_metadata without needing to name them.

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 'Exact — no guessing by eye' hints at when to prefer this over manual inspection, which is a mild usage cue. However, there is no explicit when-to-use guidance and no comparison against the closely related siblings dev_url_encoder, dev_url_reader, or live_url_metadata, so the agent must infer the boundary.

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