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

The description discloses the decision logic and data-source fallback: it uses the official real-time ETA or, failing that, the engine's own estimate, and compares it with walking time from the user's coordinates. It also names the output categories (CATCH, TIGHT, MISS, UNKNOWN), margin, and next step, adding significant value beyond the readOnly/openWorld annotations. There is no contradiction with annotations.

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?

Two dense sentences carry the purpose, method, data-source fallback, and output contract with no filler. The most important action and decision outcome are front-loaded, and every clause contributes to agent understanding.

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 no output schema, the description responsibly enumerates the main return values: decision, margin in seconds, and next reachable step. It could add exact response field names and edge-case behavior, but for a tool with six well-documented parameters and clear logic, it is largely complete.

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 baseline is 3, but the description adds semantic context by explaining how lat/lng drive walking time and how the ETA interacts with the stop and line. It clarifies the relationship among parameters rather than merely restating their schema descriptions.

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 uses a specific verb ('Decide si el usuario llega a tiempo a un autobús'), identifies the resource (a bus stop in Alicante), and explains the core comparison between vehicle ETA and walking time. This functionally distinguishes it from siblings like next_departures and find_transit_stop, which list or resolve stops rather than produce a catch/no-catch decision.

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 use case is implied by the title ('¿Me da tiempo a coger el bus?') and the opening verb, and the schema references find_transit_stop for resolving stops. However, the description does not explicitly state when to prefer this tool over next_departures or other sibling tools, nor does it mention any exclusions or fallback conditions.

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