api_cast

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

Because no annotations are provided, the description carries the full burden of behavioral disclosure. It does disclose two important traits: a known type does not guarantee interface support, and failures are reported as COM errors. It does not mention side effects, the success return value, or whether the operation mutates state, leaving some behavioral ambiguity.

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 compact and front-loaded: the core operation appears in the first sentence, followed by a concrete example and a useful caveat. No sentence is redundant or filler. It could be slightly clearer about prerequisites, but structurally it is well organized.

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?

Without an output schema or annotations, the description must carry almost all operational context. It explains the purpose and failure reporting, but an agent is left without guidance on handle provenance, library selection, return shape, or prerequisites such as an active connection. For a COM-style cast with three undocumented parameters, this is incomplete.

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 0%, so the description must compensate for the handle, library, and interface parameters. It only indirectly hints at valid interface names through the example (IPart7, IModelContainer) and does not explain what handle refers to or when to choose kAPI5 versus kAPI7. This is a significant gap for a three-parameter tool.

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 uses a specific verb and resource: 'QueryInterface to an additional installed SDK interface,' and provides a concrete example (IPart7 to IModelContainer). This makes the tool's core action clear and distinguishes it from sibling tools like api_describe_interface, which inspects rather than obtains an interface. It does not explicitly contrast itself with api_invoke, but the intent is unambiguous.

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 the usage scenario: you have a handle to one interface and want to obtain another interface on the same object. It also warns that support is not guaranteed, so the agent can expect failures for unsupported casts. However, it does not explicitly state when to prefer this over alternatives or what prerequisites must hold.

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