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

Annotations already declare read-only, non-destructive and idempotent, but the description adds the pagination behavior (40 fields per call, use start for more) and the format limitations (no XFA-only, no scanned forms). It also enumerates the returned field attributes, which is beyond what the annotations convey.

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?

Four short sentences, each carrying distinct information: trigger, return shape and pagination, safety, and unsupported formats. The trigger is front-loaded and nothing is repeated from the schema or annotations.

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?

Even though an output schema exists, the description summarizes the return fields, explains the pagination limit, and covers the main failure modes. An agent has everything needed to decide when to call it and how to page through results.

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 adds a non-obvious detail the schema lacks: the page size of 40 fields per call and how start interacts with it, which helps an agent reason about pagination.

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_form_fields' → returns each AcroForm field) and scopes it to fillable PDF forms. It is clearly distinguishable from the sibling fill_pdf_form because it mentions viewing fields and explicitly says it does not change the PDF.

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 a concrete trigger ('user attaches a fillable PDF form and wants to see its fields or wants it filled') and exclusion cases (XFA-only, scanned paper). It does not explicitly name fill_pdf_form as the follow-up alternative, so the routing is implied rather than stated.

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