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

Annotations already cover readOnly/idempotent/non-destructive/openWorld, and the description adds meaningfully on top: 'this tool only builds the link and posts nothing,' plus the split of responsibility ('the driver signs in and posts on the page'). It stops short of describing link format or validity, so not a 5.

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?

Front-loads the core purpose and the when-to-use/when-not contrast in the first two sentences, with the important 'posts nothing' caveat last. Slightly padded by the marketplace color ('riders share costs like gas and tolls'), which does not aid tool selection.

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 3-param, no-output-schema link-builder, the description covers the persona trigger, the non-mutation behavior, and the handoff to the driver on the page. Only the nature of the returned value (how the link is delivered/used) is left implicit.

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%, including date parsing rules and today's date, so the schema does the heavy lifting. The description only restates 'takes the starting place, the destination and an optional date' without adding format or constraint detail beyond it. 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+resource (build a link for a driver to post a drive) and makes the driver-vs-rider distinction explicit, which cleanly separates it from request_ride_link and search_rides. An agent can route correctly without opening the schema.

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?

Gives an explicit when-to-use trigger with a concrete user utterance example ("I'm driving to LA on Friday, can I take people?") and an explicit when-not ("not to find a ride"). The driver persona condition is the exact discriminator against the sibling tools.

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