get_subsystem_instance

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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered structurally. The description adds that the target is the 'live' (runtime) instance rather than an asset, plus the return field names, but says nothing about error/missing-instance behavior or prerequisite states (e.g., requiring PIE).

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 compact sentences with the capability stated first and the return contract second. No filler, though the parenthetical enumeration of lifetime values duplicates the schema and could be trimmed.

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?

With no output schema, the description usefully supplies the return object shape (class_name, lifetime, instance_name, instance_path), which is genuinely additive. It leaves out failure/empty-result semantics, but for a simple 2-param read lookup this is close to 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%, so both parameters are already documented in the schema, including the lifetime value set. The description merely restates 'class + lifetime category' and repeats the enum values, adding little beyond the schema. 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: 'Look up the live instance of a USubsystem' keyed by class + lifetime category. The qualifier 'by class + lifetime category' implicitly distinguishes it from the list_subsystem_instances sibling, but no sibling is named explicitly, so differentiation rests on inference.

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 lookup key (class + lifetime) implies when to use it, and the phrase 'live instance' hints at runtime context, but there is no explicit when-to-use guidance, no exclusions, and siblings like list_subsystem_instances, inspect_subsystem_instance, or is_subsystem_class_active are never mentioned as alternatives.

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