Leapfrog MCP

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

With no annotations, description carries significant burden: discloses return value ('snapshot of the new active tab'), safety constraint (cannot close last tab), and implies destructive state change.

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 sentences with zero waste, front-loaded with mechanism, default, constraint, and return value—all essential information efficiently structured.

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?

Complete for a low-complexity tool: compensates for missing output schema by describing return value, documents constraints, and aligns with 100% schema coverage.

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% with clear descriptions for both sessionId and tabIndex; description reinforces default behavior but does not add semantic depth beyond schema definitions.

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?

Specific verb 'Close' with resource 'tab' and mechanism 'by index' clearly distinguishes from sibling tools like tab_switch and tabs_list.

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?

Documents default behavior (active tab) and critical constraint 'Cannot close the last remaining tab', though lacks explicit alternative tool recommendation for that edge case.

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