session_tabs

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

With no annotations, the description carries the full burden and does so: it discloses the session-state prerequisite, the two failure modes with their status codes (409 not-open, 404 unknown identity), and that errors are returned as readable messages. It also describes the return payload shape.

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?

Front-loaded with purpose, then prerequisite, then usage, then args and returns — a clean progression with no filler. The Args/Returns block formatting is slightly verbose for a single parameter, but every line carries 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?

No output schema exists, and the description still documents the return value ({tabs, active} with element shape), the error contract, and the required prior state. Nothing an agent needs to call this correctly is missing.

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 0% and the single parameter has no schema description, so the description must compensate — it does, defining 'name' as the identity name 'exactly as profiles_list reports it', which tells the agent where to obtain the value.

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 ('List the session's open tabs') plus a scoping detail (active tab marked). The following sentence explicitly distinguishes it from siblings session_switch_tab and profile_start, so an agent can route without opening any schema.

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?

Gives explicit when-to-use ('Use this to find the index to pass to session_switch_tab') and an explicit prerequisite ('Requires a session opened with profile_start first'). The 409 failure message also reinforces the alternative ('call profile_start first').

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