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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=false, so the write/safety profile is covered. The description adds the required cost_categories:write scope, a genuinely useful auth prerequisite, but says nothing about side effects, duplicate handling, or what the response returns.

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?

Two short sentences, purpose front-loaded before the scope prerequisite. No filler or repetition, though it is quite minimal overall.

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 mutation tool with no output schema, the annotations cover the safety profile and the description covers purpose and auth scope. It is minimally adequate, but omits whether the created category's identifier is returned and how parent_id/duplicate names are handled.

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 100% with all three parameters (name, is_active, parent_id) documented inline, so the description needn't restate them. It adds no format or constraint detail beyond what the schema already carries, matching the baseline 3.

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?

States a specific verb (Create) and resource (cost category), which cleanly distinguishes it from update_cost_category and delete_cost_category in the sibling list. It does not, however, differentiate from other create_* tools or clarify what a 'cost category' is versus a work category or part category.

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?

No guidance on when to use this versus update_cost_category or list_cost_categories, and no preconditions beyond the scope note. The scope mention is a prerequisite rather than a usage-selection cue, so the agent gets little help choosing this tool.

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