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

The description reveals critical behavioral traits well beyond the sparse annotations (readOnlyHint: false, idempotentHint: true). It discloses that the tool uses 'the live Editor DOM in an isolated read-only browser, not generated or recreated UI,' returns 'no fabricated click transition' for defaults, and 'charges no generation credits' — rich, valuable context an agent couldn't infer from annotations or schema.

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 a single dense paragraph of about 150 words; each sentence earns its place by conveying a distinct aspect (capture behavior, state types, media prerequisites, technical implementation, cost). It's front-loaded with the core function and effectively structured as one main idea per sentence, though breaking into bullet points could slightly improve scannability for the agent.

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 3-parameter tool with no output schema and minimal annotation, the description provides comprehensive context: what state variations exist, media requirements, the technical execution model, and cost implications. An agent has everything needed to know when and how to invoke this tool correctly, making the description complete relative to the tool's complexity.

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?

While the schema already documents 2 of 3 parameters, the description enriches the `state` parameter's meaning by explaining the behavioral difference between 'default' and states 'with a configured interaction,' clarifying what the captured assets will include. It compensates for the coverage gap (project_id is undescribed in the schema and description, but the tool name makes it self-evident). Overall, it adds meaning beyond schema field descriptions.

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 uses a specific verb and resource ('Capture a fixed state of the real current production Switch Editor into your Editor project') and clearly differentiates itself by emphasizing it uses the live Editor DOM, not generated/recreated UI. This distinguishes it from the similarly-named siblings like add_editor_library_assets and upload_editor_media, making the tool's unique purpose unambiguous.

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?

The description provides strong usage context by explaining when to use it (default baseline capture vs. states with configured interaction) and explicit prerequisites ('Populated states require a real library image or video already attached'). However, it doesn't explicitly name when NOT to use this tool or point to specific alternatives, leaving exclusions implicit rather than stated.

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