session_activate

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

No annotations are provided, so the description carries the full burden. It discloses key matching behavior: exact IDs always win, substring hints must resolve to exactly one session or return an error listing candidates. This goes beyond the schema and clarifies the tool's execution semantics, though it does not mention underlying side effects beyond setting the active session.

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 two sentences: the first states purpose, the second explains matching rules and error behavior. Every sentence provides useful information with no repetition or fluff. The content is front-loaded, making it easy for an agent to extract key facts quickly.

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 single-parameter tool with an output schema and no annotations, the description covers purpose, matching behavior, and error handling. It could explicitly mention that sessions must already exist or direct users to session_manage, but the schema fills in the listing reference. Given the low complexity, the description is sufficiently complete.

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% for the single parameter, so the baseline is 3. The description adds value by explaining matching precedence (exact ID vs substring) and the error case, which enriches the parameter's meaning beyond the schema's description of acceptable input formats. This justifies a 4.

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 clearly states a specific action: 'Set the active Godot editor session for subsequent tool calls.' This immediately distinguishes it from sibling tools like session_manage (which likely manages sessions) and other editor operations. The verb 'set' and resource 'active Godot editor session' are explicit.

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 implies when to use it: before subsequent calls to affect which session they operate on. However, it does not explicitly contrast with session_manage or mention alternatives. The schema references session_manage for listing sessions, which adds context, but the main description leaves the 'when to use vs alternatives' slightly implicit.

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