fill

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

With no annotations, the description carries the full burden. It does disclose that the tool is 'Refused on credential fields', which is a useful behavioral constraint. However, it does not mention side effects, success/failure behavior, or any other important behavioral traits, so transparency is minimal.

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 consists of two short sentences with no wasted words. The main action is front-loaded, and the additional note about credential fields is placed logically. It is concise 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?

The tool is simple with only 2 parameters and no output schema, but the description omits critical context such as whether filling triggers events, what happens on success or failure, and how 'ref' relates to the broader tool ecosystem. It is minimally sufficient but leaves gaps for an agent making selections.

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 0%, so the description must compensate. It explains 'ref' as the field identifier, but 'text' is left entirely to inference from its name. No format, validation, or additional semantics are provided, leaving a gap in parameter understanding.

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 states 'Fill a field identified by its ref', which clearly identifies the action (fill) and the target (a field by ref). However, it does not differentiate this from the sibling tool 'type', which could also be used to populate fields, so it's clear but 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?

There is no explicit guidance on when to use this tool versus alternatives like 'type' or 'click'. The description implies use for filling fields and notes a restriction on credential fields, but does not provide context for selection among siblings or mention prerequisites.

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