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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile needs no restating. The description adds real behavioral context beyond that: the dual mode (pass a stop to get times, omit it to list stops) and the provenance of the data ('Disney's own bus tracking'). It stops short of stating freshness/update cadence, which would matter for a prediction tool.

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 when-to-use trigger and immediately followed by the parameter contract and data source. No filler or repetition beyond the single clarifying restatement of the optional-stop behavior.

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-optional-param read tool with no output schema and annotations covering safety, the description gives the agent everything needed to decide and invoke: trigger, input contract, and both call modes. The remaining gap is what the response looks like (e.g., list of upcoming times vs. single next arrival), which the agent must infer.

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% and the single parameter's own description already covers 'Stop name or ID ... omit to list stops.' The description repeats that contract in prose but adds no format, naming convention, or ID-lookup detail beyond the schema. 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 ('get bus times' for 'Walt Disney World bus') and names the exact domain it covers (resorts/stops to parks or Disney Springs). It is trivially distinguishable from siblings like parky_get_waits, parky_get_hours, and parky_get_showtimes, which cover different data.

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 a visitor asks when the next ... bus leaves'), which tells the agent precisely when to reach for it. It does not name or exclude any alternative tool, but the sibling set covers non-overlapping resources, so routing ambiguity is low.

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