session_select

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

With no annotations, the description carries the burden and does disclose key behavior: other sessions remain open untouched, and the selection governs every following tool call (ambient state). It omits what happens on an invalid or destroyed session id, which is a notable gap for a state-changing tool.

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?

Three short sentences, front-loaded with the action and then the side-effect and the id source; nothing redundant.

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?

For a one-parameter selector with no output schema, the description covers purpose, cross-call effect, and id sourcing adequately; only error behavior on an invalid id is left unstated.

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 description coverage is 100% and the single sessionId parameter is already documented as coming from session_create or session_list, so the description adds only a pointer to session_list rather than new semantics. Baseline 3 applies.

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 ('Make an existing browser session the active one') plus the effect on subsequent calls, which cleanly separates it from session_list, session_create, and session_destroy.

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 clear operating context (multi-session switching) and points to session_list for obtaining ids, but never states when this should be preferred over session_create/start_browser or what to do when no session is currently open.

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