tabs_context_mcp

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

With no annotations, the description carries the full behavioral burden. It discloses that the tool only lists tabs opened by this server in its Firefox profile (not user's own windows), that no site permission is needed, and the behavior when no group exists (reply says so, points to createIfEmpty). It also clarifies that createIfEmpty never appends a second tab. These are significant behavioral details beyond what a schema could convey.

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 and front-loaded with the core purpose. Every sentence adds value: scope, usage timing, exclusions, fallback behavior, and guidance for new conversations. No fluff or repetition.

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?

The tool has no output schema, but the description explicitly lists the returned fields (id, address, title, focus) and explains the createIfEmpty behavior. It also covers edge cases like empty groups and permission requirements. An agent has everything needed to call and interpret the result correctly.

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?

The schema description coverage is 100% for the single parameter createIfEmpty, and the schema already explains its effect. The description reiterates the 'when no group exists' context but does not add new semantics beyond the schema. Baseline 3 is appropriate.

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 opens with a specific verb and resource: 'List the tabs this session owns' and enumerates the exact fields returned (numeric id, current address, page title, focus). It clearly distinguishes itself from siblings like tabs_create_mcp and navigate by stating it is a listing tool that precedes other browser actions.

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?

The description gives explicit when-to-use guidance: run it before any other browser tool and again after tabs open or close. It also explains when to prefer tabs_create_mcp for new conversations and when createIfEmpty is relevant, providing clear alternatives and exclusions.

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