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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=false, openWorldHint=true) by disclosing the read-back verification model, the specific failure mode (`not_applied`) and what it returns, the submit-gating behavior, and the file-input override that bypasses the native file panel. This is exactly the behavioral context annotations cannot 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 the core action, then the read-back/error contract, then the submit caveat, then the file-input special case. Dense but each sentence carries distinct information; the parenthetical about JS and the native file panel is slightly verbose but justified.

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 and minimal annotations, the description fully carries the burden: it covers success verification, the failure shape, the submit handoff, and the file-input edge case. Nothing an agent needs to invoke it correctly appears 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 coverage is 100%, so the baseline is 3, but the description adds real meaning: it clarifies `target` accepts either a CSS selector or a visible label/placeholder, and that `text` is reinterpreted as a local file path when the target is a file input. That reinterpretation is the key semantic the agent needs.

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 (types text) and resource (form field, rich-text editor, or file input) on the current page, and explicitly distinguishes itself from web_click by noting it does NOT submit. An agent can identify the operation and its scope immediately.

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?

Clearly states the post-condition workflow ('Does NOT submit — use web_click on the submit button afterwards (that step is gated)') and carves out a special case for file inputs. It stops short of naming sibling alternatives like ui_type for desktop-level typing, so routing between the web and UI typing tools is left to inference.

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