call_method

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

The description goes well beyond the annotations (destructiveHint: true) by detailing argument coercion rules, error behavior ('Wrong types or counts return an ERROR (never a silent no-op)'), and return format ('Returns the result as JSON'). This gives the agent a clear picture of how the tool behaves, which is particularly valuable for a generic method invocation tool.

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 efficiently structured: one sentence for the core purpose, one for argument formatting, one for error handling, and one for the return value. Every sentence adds concrete information, and there is no redundant or filler content. It is appropriately sized for the tool's complexity.

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 complexity and lack of output schema and parameter descriptions, the description provides a strong foundation: it covers inputs, coercion, error handling, and output. However, it does not fully specify the format for 'target' and 'method' parameters, nor does it mention when the destructive hint might apply in practice. Slight gaps remain, but the description is substantially 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?

With 0% schema description coverage, the description carries the full burden for parameters, and it does so well for 'args' by explaining accepted formats for vectors, colors, and object params. However, 'target' and 'method' are only implicitly described as 'resolved object' and the method name, leaving some ambiguity about their exact format (e.g., whether target is a node path or resource path).

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 function: 'Invoke a method on a resolved object.' This is a specific verb+resource combination that distinguishes it from sibling tools like set_property or runtime_get_property, which handle property access rather than method calls. The scope is well-defined with additional details about argument coercion.

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 provides clear context on what the tool does, but does not explicitly state when to use it over alternatives or provide exclusions. It implies usage for calling methods on objects, but does not mention scenarios like setting properties or other sibling operations, leaving the decision to the agent.

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