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

No annotations are supplied, so the description carries the full behavioral burden. 'Look up' and 'check if indexed' strongly imply a read-only, non-mutating probe, and the example URL clarifies what a valid key looks like, but it never states auth requirements, rate limits, or what is returned when the URL is not indexed — the most likely failure path for a lookup tool.

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 routing instructions are front-loaded in two tight sentences with zero filler, and the negative case follows the positive one logically. The trailing '### Responses: 200 ... Content-Type: application/json' block is auto-generated OpenAPI boilerplate that adds nothing about non-200 outcomes, slightly diluting an otherwise clean definition.

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 one-parameter read tool with no output schema, the description covers purpose, valid inputs, the primary use case, and the main misuse case. The remaining gap is the not-found / no-match outcome, which matters for a tool whose stated job is checking whether something is indexed.

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%, so the baseline is 3, and the description earns above that by specifying that the URL may be clearnet, Tor .onion, or I2P, giving a literal example with query string, and carving out the app.vysion.ai/document/<id> form as invalid for this tool. That is meaning the schema's 'Full URL of the indexed page' does not convey.

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 ('Look up a document in Vysion by the URL of the indexed page') and enumerates the supported URL classes (clearnet, Tor .onion, I2P). It explicitly distinguishes itself from the sibling get_document_by_id, so an agent can pick between them without opening either 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?

Gives both sides of the routing decision: use it 'to check if a specific URL is indexed', and do NOT use it for app.vysion.ai/document/<id> links, with the concrete remedy of extracting the <id> and calling get_document_by_id. The exclusion and the alternative are named in the same breath as the use case.

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