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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses substantial operational traits: distributions only scan the newest 2000 responses, a truncated flag signals a larger total, and free-text 'Other' values should be treated as untrusted. These are exactly the behavioral details an agent cannot get from structured 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?

A single tight paragraph with the core purpose front-loaded, then parameter guidance, then the sampling limit, then the untrusted-data caveat. Every sentence contributes distinct information and 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?

With an output schema present, return values need not be explained, yet the description still previews them accurately. Combined with the sampling-limit disclosure and the security caveat, an agent has everything needed to invoke this 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?

Schema coverage is already 100%, so the baseline is 3. The description adds genuine framing by explaining excludeFields as a privacy mechanism ('keep sensitive fields out of the breakdown') rather than a mechanical field filter, which slightly exceeds what the schema text conveys.

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 gives a specific verb and resource ('Aggregate view of a form's accepted responses') and enumerates the exact outputs (total, per-field counts, value distributions), which clearly separates it from a raw response list. It stops short of naming sibling tools such as fillo_form_insights or fillo_list_responses, so the agent must infer the boundary itself.

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 offers a concrete usage hint ('Pass excludeFields to keep sensitive fields out of the breakdown'), implying when the parameter matters. However, there is no explicit when-to-use versus when-not guidance and no routing to alternative tools for related tasks.

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