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

The description discloses significant behavior beyond the sparse annotations: billing and free quota, the unavailable flatten flag, unmatched-label reporting, retention modes, and ephemeral deletion timing. This is exactly the operational detail an agent needs to set expectations and ask the user about unmatched fields.

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?

The description is dense but each sentence carries operational information. The core purpose is first, followed by value semantics, restrictions, return behavior, billing, retention, and deletion lifecycle, in a logical order with no filler.

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 4-parameter tool with an output schema, the description covers required inputs, value format, return content, cost implications, and data lifecycle. Nothing essential is missing for an agent to invoke fill_form correctly.

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?

With 0% parameter schema descriptions, the description compensates fully: values are structured by field id/label, checkboxes accept yes/no, choice fields require a valid option, flatten is reserved, and retention is ephemeral or account_default with the account setting as default. form_id is obvious from the name.

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?

The description clearly identifies the action ('fill') and resource ('PDF form'), and adds that it works from structured values keyed by field id or label. It does not explicitly contrast this with the sibling fill_batch or fill_form_from_context tools, so it stops just short of full sibling differentiation.

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?

It gives clear context for use: a ready form and structured data such as JSON or key-value answers. It lacks explicit exclusions or comparisons with sibling fill tools, so agents are not told when to prefer fill_batch or fill_form_from_context.

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