Read the page structure

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

Annotations already cover the read-only safety profile and open-world scope, so the bar is lower. The description adds genuine value: the compact-tree output format, the critical behavioral rule that unreferenced elements cannot be targeted, and a cost/performance comparison ('much cheaper'). Truncation/pagination behavior is left to the schema's cursor parameter, but this is a minor gap.

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 short sentences with zero filler. The core function is front-loaded first, followed by usage timing, the targeting constraint, and the cheaper alternative. Every sentence earns its place.

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 full annotation coverage, 100% schema description coverage, and no output schema, the description is complete: it explains what is returned, when to call it, what the references mean operationally, and when to prefer a sibling. Nothing an agent needs to invoke it correctly is missing.

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%, so all four parameters (cursor, max_tokens, session_id, interactive_only) are already documented in the schema. The description does not add parameter-specific detail, so the baseline 3 applies — the schema carries the load and does so adequately.

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 and resource: 'Return the page as a compact accessibility tree with a @eN reference on every element you can click or type into.' The distinctive @eN reference format makes the output immediately recognizable, and the mention of steel_find as an alternative helps differentiate it from at least one sibling.

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 explicit when-to-use guidance ('This is the read to use before acting'), a hard constraint that shapes usage ('Elements with no reference cannot be targeted'), and names the alternative with the condition that selects it ('If you already know what you are looking for, steel_find is much cheaper').

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