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

Annotations only flag destructiveHint, so the description's additions matter: it discloses that the call is BILLED, that the result is a short-lived ({ FileUrl } ~24h) link, and names the underlying endpoint. It stops short of describing async/polling behavior or what happens to the source document, which matters for a billed mutation.

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, front-loaded with the action and input, followed by return shape, cost, and endpoint. Nothing redundant; every clause carries information an agent can act on.

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 an 8-parameter tool with nested objects and no output schema, the description covers the essential output contract ({ FileUrl }, 24h validity) and the billing caveat. It could say more about the nested options/storage parameters and error behavior, but the schema carries the parameter detail well.

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 100%, with all 8 parameters (url, inline, options, storage, fileName, output_binary, extraHTTPHeaders, useCustomStorage) documented in the schema itself. The description only reiterates the URL input and the FileUrl output, adding no syntax or format detail beyond the schema, so baseline 3 applies.

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 (compress) and resource (existing PDF), plus the input form (a URL) and the goal (reduce file size). No sibling among the 16 tools offers compression, so this is unambiguous against the list.

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 stated goal implies when to reach for it (file too large), but there is no explicit when-to-use framing, no prerequisites, and no mention of limitations such as whether already-optimized PDFs benefit. Usage is inferable rather than guided.

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