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

Goes beyond the annotations (readOnlyHint=false, openWorldHint=true) by disclosing meaningful state effects: the tab is added to the session group and becomes the target tab, and console/network recording begins before the load. Also discloses failure behavior (load errors surfaced as errors) and the blocking/wait semantics. Missing only timeout/permission nuances, which the schema covers.

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 tight sentences with zero filler; the primary action and its state effects come first, followed by the recording and wait behavior. Every sentence carries distinct information.

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 browser-navigation tool with a fully described 4-param schema and no output schema, the description covers side effects, recording start, wait behavior, and error reporting. An agent has everything needed to call it correctly and predict its effects.

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 coverage is 100%, so the schema already documents url, timeoutMs, waitUntil, and background. The description adds only a clarifying note that 'none' disables waiting, leaving background and timeout semantics entirely to the schema — appropriate baseline for full coverage.

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 ('Opens a URL in a new tab') plus the resulting state changes: joins this session's tab group and becomes the session target tab. The 'new tab' framing implicitly sets it apart from navigate/tab_select siblings without needing their schemas.

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?

Conveys the operational context (load capture, blocking until load unless waitUntil is 'none') but never names an alternative such as navigate for reusing an existing tab, nor any when-not condition. Usage is implied by describing behavior rather than stated as guidance.

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