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

Annotations already declare readOnly=false, destructive=false, idempotent=true and openWorld=false, so the description only has to add context beyond that. It does: an account requirement ('Needs their WithBy account'), the append-to-existing-list nature of the write, the capacity bound, and the fact that this mutates the same list as the website action. It does not say what happens to ids already on the list (relevant given idempotentHint=true) or what a successful call 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?

It is a single front-loaded sentence: trigger first, mechanism second, boundary last, with no filler. It is dense to the point of being a long run-on colon construction, and the 'same list as Save for my drive on withby.ai' clause could be tightened, but nothing is wasted.

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 one-parameter append tool with full annotation coverage and no output schema, the description supplies the non-obvious pieces an agent needs: authentication requirement, target list identity, and domain scope. The one remaining gap is outcome semantics — duplicate ids and the success response are unspecified, which matters slightly because no output schema exists to fill that in.

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% on the single story_ids parameter, so the schema already explains format, bounds and provenance. The description's restatement of the 1–50 range and the id source duplicates that rather than adding meaning, so the 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 and resource: it adds 1 to 50 stories, by id, to the user's WithBy next-drive list, and anchors that list to the visible 'Save for my drive' action on withby.ai. The sentence 'Not for navigation, bookings or places outside Washington' plus the id-provenance clause ('the ids the story, stretch and nearby-stories answers give') distinguishes it from siblings such as my_next_drive, story and stories_near.

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?

Opens with an explicit trigger ('Use this when someone wants particular stories saved for their next drive') and gives clear exclusions (no navigation, no bookings, no places outside Washington). It stops short of naming the sibling tools to redirect to — e.g. my_next_drive for viewing the list, stories_near for discovery — so the alternative routing is left implicit.

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