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

With no annotations, the description carries the full burden. It discloses the sandboxed iframe context, three text fields, empty surface return values, 404 behavior for invalid slugs, and the viewer role requirement. This exceeds typical transparency and gives the agent a strong behavioral model.

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?

Four sentences, each adding value: what it does, what HTML surfaces are, how to use parameters, and edge cases. Front-loaded with the core purpose. No fluff or repetition of schema details verbatim.

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 read-only tool with 2 params and no output schema, the description explains the return structure (html/css/js), empty-state behavior, error handling (404), permissions (viewer role), and how to enumerate surfaces. It is complete for an agent to invoke correctly without additional information.

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%, with both parameters clearly described in the schema. The description adds no new parameter-specific meaning beyond what the schema already provides; it repeats the omit-to-read-primary behavior. Extra context (empty returns, 404) is about behavior, not parameter semantics. 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?

The description clearly states the tool reads an HTML surface's body, specifying the resource (HTML surface) and the action (Read). It distinguishes from sibling tools like list_surfaces (enumerate) and update_html (modify) by focusing on body retrieval. The phrase 'Read an HTML surface's body' is specific and purposeful.

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 instructs to use list_surfaces for enumeration, naming an alternative tool. Provides clear guidance on when to omit or pass surface_slug for primary vs. specific tabs. Also includes behavioral outcomes (empty surfaces, 404) that help determine when this tool is appropriate.

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