session_activate

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

With no annotations, the description carries full responsibility for behavioral disclosure. It explains precedence rules ("An exact id match always wins"), substring resolution requirements ("must resolve to exactly one session"), and error behavior ("returns an error listing the candidates"). This goes beyond the schema by detailing matching logic and failure modes, but does not cover broader effects like session persistence or side effects.

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 concise and front-loaded: the first sentence states the purpose, followed by a compact paragraph on matching rules. Every sentence contributes meaningful information—no filler, no repetition of schema content. The structure aids quick comprehension.

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 setter tool with a simple state-changing operation, the description covers essential context: what it does, how to identify the session, and error behavior. An output schema exists, so return values are presumably documented there. The description is complete enough for an agent to invoke correctly without additional information.

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 already provides 100% coverage for the single parameter, describing format and examples. The description adds further meaning by enumerating the fields matched by a substring hint (short name, project_path, session_id) and the precedence rule for exact IDs. This augmentation clarifies edge cases not fully documented in the schema.

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 the tool's purpose with a specific verb and resource: "Set the active Godot editor session for subsequent tool calls." It also distinguishes itself from siblings like session_manage by focusing on state setting rather than session management/list operations. The matching semantics further clarify its role.

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 the tool: before subsequent calls to target a specific session. It specifies the input format and matching behavior, but does not explicitly mention alternatives or exclusions (e.g., when to prefer session_manage). It is clear context without explicit negative guidance.

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