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

Annotations already declare readOnlyHint=false, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description goes beyond them with genuinely useful behavior: slug auto-generation when omitted, the idempotent empty-200 response on a duplicate slug with no duplicate created, and the closed-world account/trip boundary. It stops short of describing the success response shape, though an output schema exists.

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 front-loaded sentences: purpose first, then API behavior, then scope. Efficient overall, with only mild redundancy from restating the duplicate-slug rule that the slug parameter schema already covers.

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?

With annotations covering safety, 100% schema coverage, and an output schema handling return values, the description supplies exactly the missing pieces: ownership scope, closed-world boundary, and idempotency semantics. An agent has everything needed to invoke it correctly.

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%, so the schema already documents all five parameters including slug generation and the duplicate-slug outcome. The description largely repeats the slug rule rather than adding new meaning, and says nothing about how the raw 'data' object interacts with typed top-level fields beyond what the schema states. Baseline 3 applies.

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') plus a specific resource ('custom activity category') and adds an ownership qualifier ('owned by the authenticated user'). The create-vs-list/show/update/delete distinction from siblings is unambiguous from the name and opening sentence.

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 implies usage (creating a user-owned category) and explains the duplicate-slug outcome, which is a de facto precondition check. However, it never explicitly says when to prefer this over alternatives such as checking tripsy_categories_list first or using tripsy_categories_update for existing categories, and gives no exclusion guidance.

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