list_tabs

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

The description goes well beyond the readOnly/idempotent annotations by disclosing concurrency behavior, snapshot isolation of the default session, and the bridge-reservation semantics on timeout versus pending mutations. This is exactly the kind of non-obvious behavior an agent needs to invoke the tool safely.

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 front-loaded with the primary purpose and then compacts several distinct behavioral facts into tight sentences with no filler. Each sentence adds new information about scope, concurrency, session handling, or reservation semantics.

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 description is thorough for a tool with no input parameters and an output schema, covering concurrency and session isolation. The main gap is that it never clarifies how list_tabs differs from the sibling list_all_tabs, and the session_id instructions assume context the schema does not expose.

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?

With zero parameters and 100% schema coverage, the baseline is 4. The description adds relevant session_id context even though it is not a schema property, which is helpful for understanding the tool's operating model, though it slightly muddles the fact that no input parameters are accepted.

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 uses a specific verb and resource: 'List connected tabs across all connected browsers' and states the key output fields (browser, session id). It is clear at a glance, but it does not explicitly differentiate itself from the closely named sibling list_all_tabs, so the agent must infer the distinction.

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 concrete operational context: it can answer while another tool is running, and it instructs agents to pass session_id explicitly when sharing one MCP process. It does not, however, state when to prefer this tool over list_all_tabs or other sibling alternatives.

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