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

The description goes beyond annotations by explaining real behavioral consequences: total_cost immediately consumes the material budget, is_billable and markup_percentage determine client charges, and non-billable lines still consume budget but earn nothing. It matches the mutation semantics of readOnlyHint=false and adds valuable side-effect detail.

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?

Three sentences, with the core action front-loaded and every following sentence adding substantive financial or billing context. There is no fluff and no repetition of schema defaults.

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?

For a 10-parameter mutation tool with no schema descriptions and no output schema, the description leaves meaningful gaps: how unit_cost and quantity relate to total_cost, how markup_percentage is applied, and what the response looks like. It is adequate for tool selection and high-level input understanding, but not fully complete for precise 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?

With 0% schema description coverage, the description adds essential meaning for the least obvious parameters: total_cost, markup_percentage, is_billable, and workspace currency. It does not explain the relationship between unit_cost, quantity, and total_cost, or the exact markup formula, so it is not fully complete.

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 a specific action and resource: 'Add a material line to a project.' This distinguishes it from sibling tools like projects_update_material, projects_delete_material, and projects_get_materials. It also adds relevant domain context about material budgeting.

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 first sentence gives unambiguous usage context—use this tool to add a new material line to a project. It does not explicitly list alternatives or exclusions, so it misses the strongest 'when not to use' guidance, but the intended situation is clear.

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