Fill Form

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

Goes well beyond annotations: it discloses that disabled/readonly/non-input targets fail with a reason, that all fields are attempted in order with per-field results, that `ok` is false if any field fails and `error` names the failures, and that values are not echoed back. These are exactly the mutation/partial-failure traits an agent needs and that the annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=false) do not 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?

Front-loads what the tool does, then covers failure semantics, then the no-submit caveat. Every sentence carries information — no restated boilerplate or filler — and it fits in five tight sentences.

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 no output schema, the description still explains the return contract (`ok`, `error`, per-field results, values not echoed) and the post-condition (must click submit separately). Nothing an agent needs to call this correctly is missing.

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 description coverage is 100%, so both top-level parameters and the nested field properties are fully documented in the schema itself. The description adds little parameter-level detail (e.g., it does not explain tab_id behavior or the 50-field limit), so it sits at the documented-schema baseline.

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 ('Fill several fields in one call') and immediately distinguishes itself from the single-field `fill` sibling by describing batching semantics. An agent can tell it apart from `fill`, `type`, and `select_option` without opening any schema.

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?

Usage context is clear — use this when setting multiple fields at once, since each field behaves 'exactly as fill would'. It also gives the follow-up step ('Does not submit: click the submit button afterwards'). It never explicitly says 'use fill for a single field', so the alternative is implied rather than named.

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