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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile and external-service nature are covered. The description adds that it queries Google Flights and supports round trips, but says nothing about result volume, rate limits, caching, or failure modes for a live external search.

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?

A single front-loaded sentence with no filler, stating the action, provider, and trip types before any detail. Every clause earns its place for a tool of this simplicity.

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 an output schema present, return values need no explanation, and annotations cover safety and openness; the schema fully documents all four parameters. The only real gap is the absence of usage context, so the definition is nearly but not fully 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 coverage is 100%, with each parameter fully documented (IATA codes with patterns, date formats, return_date defaulting to null). The description's 'one-way or round-trip' phrasing hints at how return_date is used but adds no format or syntax detail beyond the schema, 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?

The description names a specific verb ('Search'), a specific resource ('Google Flights'), and the supported trip shapes ('one-way or round-trip flights between two airports'). It is far more specific than a tautology, though it does not explicitly distinguish itself from any alternative since the only sibling (server_status) is unrelated.

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?

Usage is only implied: 'search flights' plus the required origin/destination/outbound_date schema makes the intent obvious, but the description never states when to use this tool, when not to, or any prerequisites. There is no competing sibling to route against, so the omission is low-impact.

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

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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered and the description only needs to add context. It adds that this probes the flight search server specifically, but says nothing about what a failed check looks like or how results should be interpreted beyond the output schema.

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?

A single front-loaded sentence with no filler, perfectly sized for a no-argument probe. Every word earns its place.

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 an output schema present, the description needn't explain return values, and a zero-param health check needs little more. The only mild gap is not indicating how to act on a negative result (retry, abort, report).

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The empty schema plus the sentence leaves no ambiguity about invocation.

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 ('Check') and a precise resource ('the flight search server is running'), which is a health/liveness probe rather than a search — clearly distinct in kind from search_flights_tool. It doesn't explicitly name the sibling, but the action and object are unambiguous.

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?

For a zero-parameter health check the intended usage is largely self-evident, so guidance is implied rather than stated. It never says when to call it (before a search? on error?) or that there are no alternatives, leaving the agent to infer context.

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