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

Annotations already provide readOnlyHint, idempotentHint, and destructiveHint, covering safety. The description adds value by noting it is PAID, returns the complete file inline, lists components to install, and gives mounting instructions – important behavioral details not captured in annotations.

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?

Three sentences with no waste. The PAID marker is front-loaded, the core purpose is stated first, and the sibling alternative and prerequisite are given succinctly. Structure is logical and scannable.

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 single-screen emission tool with no output schema, the description covers the return contents (file, components, mounting) and the required input. It doesn't detail error cases or edge limitations, but given the simplicity and schema completeness, it is largely sufficient.

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 schema documents both parameters. The description adds meaning by clarifying that compositionId is the 'share code' and explaining the output includes file, components, and mounting, which enriches understanding of how parameters drive the result.

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 clearly states the verb 'emit' (turns into a TSX file) and the resource (one composed screen), and immediately contrasts with the sibling tool emit_app for whole apps. This distinguishes it from alternatives without ambiguity.

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 explicitly names emit_app as the matching tool for whole apps with navigation and a tab bar, implying this tool is for single screens. It also states the prerequisite of needing the share code from the App Builder, giving clear context for when to use it.

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