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

With no annotations, the description carries the burden of behavioral disclosure. It explains the value formats for answers (date, checkbox, radio/dropdown), the optional signing, and the base64 output, which is helpful. However, it omits potential side effects like credit costs or account creation, which are only in the schema descriptions, and does not discuss error behavior or reversibility.

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 only two sentences, front-loaded with the main purpose and output. It packs essential details (answers format, get_template prerequisite) without unnecessary fluff, making it appropriately sized and well-structured.

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 tool with 8 parameters, a nested answers object, and no output schema, the description provides the core context: what it does, the answer format, and a key prerequisite. The detailed schema covers the remaining parameters, and the description mentions the base64 output to compensate for the missing output schema. It does not explain how to choose between slug/id or the ai/account_id interactions, but those are in the schema.

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 meaning beyond the schema by detailing the answers object: date format as 'TT.MM.JJJJ', checkbox as booleans, and radio/dropdown as options. This goes beyond the schema's 'String or Boolean' and enriches the understanding of key parameters.

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 states the tool fills a template and optionally signs it, producing a PDF as base64. It names the specific resource (template) and action (fill), but does not explicitly contrast with sibling tools like fill_pdf, so it lacks explicit 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 provides a clear usage context by instructing to fetch field names with get_template first, which is a solid prerequisite. However, it does not mention alternatives or when not to use this tool, so it stops short of full exclusion guidance.

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