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

With no annotations, the description carries the full burden and does so well: cost ($0.01/call), billing source (shop credits, existing key, top-ups paused), failure pricing (failed or empty call is free), input limits, and the no-OCR limitation. This is exactly the operational context an agent needs before spending credits.

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?

A single dense sentence with no filler, front-loading the core action and then layering limits, flags, cost, and the no-OCR caveat. Every clause earns its place.

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, no-output-schema tool, the description still discloses return shape (page count, likely_scanned flag), cost model, and failure behavior. Nothing needed to call it correctly is missing.

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% for the single 'url' parameter, and the schema already specifies it must be a public http(s) URL of a PDF. The description reinforces 'public PDF' but adds no syntax or format detail beyond the schema, so the baseline of 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 and resource ('Convert a public PDF to plain text') and immediately scopes the result ('full extracted text in one call'). It is unambiguous and clearly distinct from every sibling tool, none of which touch PDFs.

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 clear usage conditions: input must be a public PDF, text-based only, no OCR, with explicit size ceilings (25MB / 500k chars). It does not name alternatives, but no sibling tool overlaps this capability, so the routing gap is minimal.

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