Click a widget

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

Annotations declare destructiveHint=true and idempotentHint=false, and the description adds genuinely new behavior: the tree is returned after redraw, multi-match selectors are rejected rather than guessed, and clicking toggles checkboxes. The ensure parameter's conditional idempotency is a nuance the boolean annotation cannot express, and it complements rather than contradicts it. It does not say what side effects a click may trigger beyond toggling, so not a 5.

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?

Two sentences, front-loaded with the core action and outcome, then the refusal condition and the ensure pattern. Every clause carries information; the 'clicking toggles a checkbox' aside is the only part that could be trimmed. No preamble or filler.

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 does the right thing by stating the return value (the tree after redraw), and it covers the selector's single-match constraint and the idempotency escape hatch, which are the risky behaviors for a destructive click. Minor gaps remain — what 'selector' is composed of and what happens on refusal — but they are not blocking.

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 every parameter — including the selector fields and the two enums — is already documented in the schema. The description's explanation of ensure largely restates what the schema says ('Click only if the widget is not already in this state... Makes the call idempotent'), adding only the concrete 'checked/unchecked/selected' framing. Baseline 3 is appropriate.

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?

It states a specific verb and resource — clicking the centre of the single widget matched by a selector — and adds the post-condition (returns the tree after redraw). That is well beyond a tautology. It never names or contrasts with siblings such as press_key or type_text, so an agent gets no explicit routing help, which caps it at 4.

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 gives two concrete usage rules: the call is refused when the selector matches more than one widget, and ensure should be passed when a step must be safe to repeat (click only if not already in the target state). That is real when-to-use guidance. It stops short of stating when to prefer this tool over press_key/type_text or what to do on refusal, so no exclusions are covered.

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