Set Active Instance

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

With no annotations, the description carries the full disclosure burden. It does reveal one non-obvious behavioral trait: the setting only affects calls that omit session_key, implying explicit session_key usage overrides it. It omits whether the selection persists across reconnects, is scoped per client or globally, or what happens if the chosen instance disconnects.

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?

Two short sentences, front-loaded with the core effect before the situational hint. There is no filler, hedging, or redundancy.

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?

An output schema exists and the sole parameter is fully documented, so return values need no explanation. For a simple default-target selector the description is nearly sufficient, with only the persistence/scope of the setting left implicit.

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 parameter already documents that instance_id is a 'session_key from list_sessions'. The description adds only the routing implication of omitting session_key, not further format or validation detail, so the 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 ('Choose which connected Maya instance handles calls that omit session_key'), which precisely describes the state change and its effect on subsequent routing. It is clearly distinguishable from list_sessions, which supplies the instance_id, and from execution tools like execute_python.

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 an explicit condition for use: 'Useful when several Maya instances are open.' Combined with the parameter's reference to list_sessions, an agent can infer the workflow (list_sessions -> set_active_instance). However, it does not state when NOT to use it, nor that it is unnecessary for single-instance setups or for calls that pass session_key explicitly.

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