List PDF form fields

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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description adds real value beyond that by disclosing the return shape (field name, label, type enum, page, current value, options, required/read-only/multi-line) and the reading-order guarantee. It omits what happens on a PDF with no fillable fields — empty result vs. error — which is the one behavioral gap.

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 sentences, front-loaded with the core action and the return inventory, followed by the actionable handoff to pdf_form_fill. The trailing web-version URL is small and doesn't displace the substance; nothing is padded.

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 must carry the return contract — and it does, enumerating every field attribute an agent needs to plan a fill. The only missing piece is edge-case behavior (non-form PDF, encrypted PDF), which keeps it from a 5.

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%, and the single 'file' parameter is fully documented in-schema (local path relative to --root, or raw/base64 data URI). The description adds no parameter-level detail of its own, so the baseline 3 applies — the schema does all the semantic work.

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 ('List the fillable fields of a PDF form') and then enumerates the exact per-field attributes returned, which distinguishes it cleanly from pdf_info or pdf_to_text. An agent can tell instantly that this is the form-introspection tool, not a generic text extractor.

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?

Explicitly routes the agent forward: 'Use the names with pdf_form_fill,' which is the natural alternative-sibling handoff. It does not state when NOT to use it (e.g., for non-form PDFs, where pdf_info or pdf_to_text would be the right call), so it falls short of full when/when-not guidance.

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