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

No annotations, so the description carries the burden and does well: it discloses the 10 MB packed size limit, the ownership precondition, the mutation nature ('Replace'), and a required follow-up step. It stops short of saying whether the replacement is immediate/reversible or what happens on invalid HTML.

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 short sentences, front-loaded with the core action, then the follow-up requirement, then the alternative tool. No filler or repetition.

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 annotations and no output schema, the description supplies the essential workflow (replace, then submit), the resource limit, and fallback routing, which is enough to call it correctly. Minor gaps remain around failure behavior and whether the change is staged or live.

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% and all three parameters are documented there, so the baseline is 3. The description adds only marginal meaning for the html payload (size cap) and slug (ownership) beyond the schema.

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+resource ('Replace the HTML of a web app you own') with a scope qualifier and a size bound. It clearly separates this tool from submit_app and publish_app, which are named in the text.

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?

Explicitly says what it does NOT do ('does not submit; call submit_app afterwards') and routes to the correct sibling for multi-file or icon cases ('use publish_app with the slug instead'). When-to-use and when-not-to-use are both covered.

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