set_value

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

Annotations cover the safety profile (readOnly=false, destructive=true, idempotent=true). The description adds non-obvious behavioral context: works on background apps without keyboard or clipboard focus, and is language-agnostic. It could say more about the destructive overwrite nature, but the annotation plus this context is solid.

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 sentence front-loading the core action, followed by the key differentiator. No waste.

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?

For a 5-param, 1-required mutation tool with no output schema and annotations carrying the safety profile, the description conveys the essential differentiator and behavioral context. Minor gaps remain on element-targeting precedence, but nothing critical 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 80%, so the schema already documents id, app, role, and label. The description adds no parameter-level meaning (no note on which of id/label/role takes precedence), so baseline 3 applies.

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: set a text field's value via accessibility. Clearly distinguishes from sibling 'type' by emphasizing direct accessibility-setting without keyboard/clipboard. Scope is a bit narrow ('text field') given the schema allows role/label matching of arbitrary elements.

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?

Implies usage context (background apps, no keyboard/clipboard needed), which hints when to prefer it over type/key. But it never explicitly names alternatives or states when NOT to use it, nor the relationship with the 'inspect' tool to obtain ids.

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