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

Annotations already cover read-only, non-destructive and closed-world, so the bar is lower, but the description still adds real context: results are predictions sourced from Disney's own bus tracking (i.e., estimates, not guaranteed schedules), and omitting the stop switches the tool into a stop-listing mode rather than failing. It does not describe freshness, refresh cadence, or how far ahead predictions run.

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 short sentences, front-loaded with the trigger condition, then the argument behavior, then the data provenance. Nothing is redundant and no sentence lacks a purpose.

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 single-optional-parameter read tool with annotations covering safety and no output schema, this covers trigger, parameter behavior and data source adequately. It leaves the return shape (e.g., whether times are grouped per destination park) implicit, which the missing output schema would otherwise have carried.

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 coverage is 100%, so the 'Bus stop ID or name; a resort name works ... Omit to list the stops' semantics are already documented in the schema. The description restates the same stop/no-stop dichotomy without adding format, casing, or ambiguity-resolution detail beyond it, so 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?

The description names a specific verb and resource: retrieving the next Walt Disney World bus departure from a resort or stop toward a park or Disney Springs. The purpose is unmistakable and clearly distinct from sibling tools covering waits, hours, crowds and showtimes, though it never names a sibling explicitly to route against.

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?

It opens with an explicit trigger ('Use this when a visitor asks when the next ... bus leaves'), which is stronger than most definitions, and it explains the no-argument path ('without one, it lists the stops'), giving the agent a discovery fallback. It stops short of stating when-not to use it or pointing to an alternative tool.

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