Create Direct Cost Item

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

The description goes beyond the annotations by explicitly stating that calling it again creates another record (non-idempotent), that it returns the new id with HTTP 201, and by listing common error statuses (401, 403, 404) with likely causes. This gives the agent concrete operational expectations absent from the annotations.

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 front-loaded with the primary purpose and is information-dense, with each sentence offering value (limit, default, return behavior, errors, API reference). It is not overly verbose, but the internal inconsistency about project_id being both required and defaultable makes it slightly less clean than a 5.

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?

The description covers return value (HTTP 201 with new id), error handling, size limits, defaulting behavior, required parameters, and API endpoint. It does not detail the nested direct_cost object structure or the multipart/form-data requirement for attachments, but the schema and API reference partially fill these gaps, making the description reasonably complete for invocation.

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 documents all three parameters (100% coverage), so the baseline is 3. The description adds a note about project_id defaulting to the configured project, but this directly contradicts the schema's required field list and the description's own 'Required parameters: project_id, direct_cost' statement, creating ambiguity rather than clarifying parameter semantics.

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 begins with 'Create a new Direct Cost Item in the specified Project', which is a specific verb+resource statement. It distinguishes itself from sibling tools like create_direct_cost_line_item by naming the Direct Cost Item and providing the endpoint POST /rest/v1.1/projects/{project_id}/direct_costs.

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 for when to use the tool, including required parameters (project_id, direct_cost), a limit of 100 line items, and project_id defaulting behavior. However, it does not explicitly name alternative tools or explain when not to use it, so it stops short of a 5.

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