Add an element to the current project

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

Beyond the annotations (readOnlyHint=false, destructiveHint=false), the description explains key behavioral aspects: the element is validated as part of the whole project before being added, and unrecognized keys are flagged. This gives the agent insight into error handling and validation behavior, which is not evident from annotations alone.

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 concise yet information-dense. Each sentence serves a purpose: the first defines the core function, the second explains default vs nested behavior, the third lists supported element types, the fourth differentiates from set_project, the fifth describes validation, and the sixth directs to get_schema. No filler 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?

Given the tool's complexity (nested element object, three parameters, an output schema exists), the description is comprehensive. It covers all essential aspects: purpose, placement behavior, supported element types, alternative tools, validation, and parameter semantics. The reference to get_schema handles per-type fields, and the output schema renders return-value documentation unnecessary. No significant gaps remain.

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 input schema already has 100% coverage with descriptions for all parameters, but the tool description adds meaningful value by explaining the semantics of parent_id (top level vs. nested) and project_id (omitted for single local project). It also clarifies that the element must include a type and is a valid schema element, enriching the structured data with context that aids correct parameter construction.

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 purpose: 'Append a single element to an existing project.' It specifies the resource (project) and action (add element), and distinguishes itself from set_project by noting that set_project is for creating compositions or adding multiple elements at once. This makes the purpose unambiguous and well-differentiated from siblings.

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 explicit usage guidance: it notes that by default the element is added at the top level, and parent_id is used to nest it into a group. It also gives a clear alternative: 'To create a composition or add several elements at once, build the JSON and use set_project instead.' Furthermore, it advises calling get_schema(element_type) for exact fields, giving the agent actionable paths for correct usage.

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