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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false. The description adds critical behavioral context: it explicitly states 'This operation does not navigate, reload, click, type, or otherwise modify the current page' and explains the edge case 'If no browser session is active, it returns {"running": False} instead of attempting to access a page.' This goes beyond the annotation flags and clarifies exact behavior when no session exists.

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 well-structured: first sentence states purpose, then usage context, then return values, then tool selection, then edge-case behavior. It is front-loaded with the core purpose and each section earns its place. Despite length, it is organized with clear headers (Returns:, Tool selection:) making it easy for an agent to scan.

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 zero parameters, the description fully explains the return dictionary fields (running, url, title, origin, user_agent) and the behavior when no session exists. It also covers the read-only nature and contrasts with siblings. With an output schema present (as indicated by 'Has output schema: true'), the description need not repeat all return details, but it still provides a concise summary. Complete for a metadata-fetching tool.

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?

Tool has 0 parameters, so schema coverage is trivially 100%. Per rubric, 0 params baseline is 4. The description does not need to explain parameters since there are none. It does implicitly clarify that no arguments are required, but no additional semantics are needed.

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 states a specific verb and resource: 'Get current browser session and page metadata.' It explicitly lists the metadata types (URL, title, origin, user_agent) and contrasts with siblings by stating what it does NOT do (inspect content, find elements, check visibility). This distinguishes it clearly from get_content, find_elements, check_if_condition, etc., with no ambiguity.

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 'Tool selection' rules: 'Need URL, title, origin, or User-Agent -> use get_page_info' and contrasts with alternatives like get_content, find_elements, check_if_condition, wait_for_condition, assert_condition. Also states primary use case: 'determining where the browser currently is after navigation, clicks, form submissions, redirects, reloads, or tab switches.' No ambiguity about when to call this tool.

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