get_active_controller

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

With no annotations, the description carries the behavioral burden and does disclose the return semantics: controller name, source ('session' from select_controller vs 'default'), and that both are None when neither is set. It does not explicitly declare the read-only/no-side-effect nature or any auth/rate-limit constraints, but for a zero-param getter this is reasonably transparent.

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 sentences, front-loaded with purpose before the Returns block. No redundant or filler content; the return-source detail is useful and compact.

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?

Given the tool's simplicity (no params) and the presence of an output schema, the description supplies enough purpose and behavior for correct invocation. It leaves out usage-guidance details, but those are covered under usage_guidelines rather than completeness.

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 tool takes zero parameters, so there is no parameter semantics to document. Per the calibration rule, a 0-param tool with high schema coverage has a baseline of 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?

States a specific verb ('Show') and resource ('which controller a tool call without ``controller`` would target'), and names select_controller as the source for session-scoped controllers, distinguishing it from list_controllers and select_controller. An agent can tell it apart from siblings without opening schemas.

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?

Provides no explicit when-to-use guidance or exclusions. It does not tell the agent when to prefer this over list_controllers or select_controller, nor does it state prerequisites such as needing an active session. Usage is only inferable from the purpose statement.

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