open_tab

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

Details behavioral traits: tab persists across calls, need to read_tab to see content, close_tab when finished. Also describes return value (tab_id, settled url, element ref count). No contradictions with missing annotations.

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?

Concise and well-structured: opens with purpose, follows with usage guidance, then parameter description, then return value. Every sentence adds value; no unnecessary words.

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?

Fully addresses the tool's purpose, usage context, parameter constraint, behavioral lifecycle, and return value. Given the simplicity (1 param, output schema exists), the description is complete and leaves no ambiguity.

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?

Adds essential constraint beyond the schema ('must include http:// or https://'). With 0% schema coverage, the description fully compensates by explaining the parameter's meaning and requirement.

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?

Clearly states the action ('Open a webpage in a persistent browser tab and return a tab_id handle') and distinguishes from sibling tools by specifying when to use (for interaction) versus when to prefer other tools (plain reading).

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 provides when to use (interact with the page) and when not to (plain reading), listing specific alternative tools (fetch_snippet, summarize, etc.) and the required next steps (read_tab, close_tab).

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