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

Explicitly states it reads the .recipebooq/files.json manifest, never reads or rewrites source, and returns a line to add rather than overwriting a file. This is unusually clear about side effects and non-effects.

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?

The description is dense but compact, packing key workflow information into two sentences. Somewhat run-on due to the em-dash clause, but no fluff.

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?

Given the absence of an output schema, the description explains the core workflow (manifest read, route tree, line edit) and the intended context (already exported app). It doesn't specify return format, but that is not required here.

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 descriptions cover all four parameters, but the tool description itself does not add additional parameter-level detail. Since schema coverage is 100%, this meets baseline but doesn't exceed it.

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?

Clearly states it adds one new screen to an already exported app, distinguishing it from emit_screen/emit_app by focusing on registration and navigation rather than creation. The verb 'Add' and resource 'screen to an app' are specific.

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?

Provides context that it is for apps already exported and that it uses the manifest to determine the route tree, implying it should be used when adding a screen to an existing app's navigation. Does not explicitly name alternatives, but the 'already exported' condition gives enough guidance.

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