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

Annotations cover the safety profile (not read-only, destructive, idempotent), and the description adds substantial context they don't: uploads persist per token between calls, pdf_files lists them, pdf_delete_upload removes one, generated files return a download link valid one hour, plus concrete limits (256 KB body / ~190 KB PDF, 2 MB url cap, 10s timeout, 3 redirects, public hosts only). That is exactly the operational detail an agent needs before spending a turn on a large payload.

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?

Front-loaded with the core model and the sibling routing before the limits, and nearly every sentence carries new information. It is a single dense paragraph, though, so the size/fetch limits run together with the workflow guidance and could be easier to scan as separate lines.

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 3-parameter upload tool with no output schema, the description covers the full lifecycle (upload, reuse by name, list, delete, expiry of generated download links) and all failure-relevant limits. Nothing an agent needs to call this correctly or recover from a size error 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%, so the baseline is 3; the description earns more by explaining *why* url beats pdf_base64 above ~10 KB (pasting large base64 stalls the turn) and by tying `name` to later use as `path`. Minor inconsistency: the description says the name is "1-64 characters" while the schema sets maxLength 70 — the stricter prose is the safer read, but the mismatch is worth noting.

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 ("Send a PDF to this hosted endpoint") and immediately explains the non-obvious model: no filesystem, so the file is uploaded once and referenced by name. It explicitly names the sibling tools (pdf_info, pdf_merge, pdf_text, etc.) that consume the uploaded file, so an agent can place it in the workflow without opening another 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 explicit when-to-use routing: upload here first, then pass the name as `path` (or in `paths`) to the listed sibling tools. It also states the mutual-exclusion rule ("Give exactly one of pdf_base64 or url") and a decision rule for choosing between them (url recommended above ~10 KB, with the reason).

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