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

With no annotations, the description carries the transparency burden. It discloses that the data is real-time and enumerates the fields returned (countdown, platform, delay, status), which is useful. It does not cover side effects, data-source caveats, or failure behavior, but as a read-only getter this is a moderate gap, not a contradiction.

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?

Single sentence, front-loaded with the core purpose, with the result fields packed in without waste. Every part of the sentence 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?

For a two-parameter read-only lookup with no output schema, the description supplies enough shape of the response (countdown, platform, delay, status) and the object type (stop/station). It is slightly light on usage context, but the schema covers parameter formats, and nothing essential is missing for invoking the tool.

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 schema already documents city and stop_id thoroughly. The description adds only the generic 'stop or station' framing and does not contribute new parameter semantics beyond the schema.

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 precise verb+resource ('Gets real-time departures') and lists the key result fields (live countdown minutes, platform, delay, status). This makes it clearly a live-departure lookup for a stop/station and distinguishes it from sibling tools like list_routes, get_route_stops, and get_service_alerts.

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 intended context is clear: use this tool when an agent needs live departure information for a specific stop or station. It does not explicitly state when not to use it or name alternatives, but no conflicting guidance is present.

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?

With no annotations, the description carries the full behavioral disclosure burden. It only states what the tool retrieves; it does not mention read-only safety, response format, error behavior, direction handling, or any other runtime behavior. This is a noticeable gap for an unannotated 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?

One clean, front-loaded sentence with no filler. Every word contributes to the purpose, and the description is appropriately sized for this simple tool.

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?

The description plus full schema coverage gives enough to attempt a call, but with no output schema and no annotations, details like return shape, ordering, and city/route constraints are missing. It is adequate but not complete for an agent operating independently.

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 schema already documents city, route_id, and direction. The description adds minimal semantic context beyond mentioning 'route', which is already in the schema. Baseline 3 is appropriate.

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 action ('Retrieves stops and stations') and a specific resource ('transit route'), and it distinguishes itself from sibling tools like get_departures and get_service_alerts. An agent can clearly tell this is the route-stops lookup tool.

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 description implies use when stop/station information for a route is needed, but it gives no explicit when-to-use or when-not-to-use guidance, nor does it mention alternatives. The usage context is inferable but not stated.

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?

With no annotations, the description carries the full burden of behavioral disclosure, but it only says the data is 'real-time.' It does not mention authentication needs, rate limits, response shape, or any side effects. This leaves important operational behavior undisclosed.

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 11-word sentence that is front-loaded with the action and resource. There is no filler or redundancy, and it 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?

For a simple read tool with full parameter schema coverage, this is mostly adequate. However, without annotations or an output schema, the description does not disclose output format, pagination, or filtering behavior, so there are clear gaps an agent would need to 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%, so the baseline is 3. The description adds no parameter-specific meaning beyond what the schema already documents, such as how route_id filters alerts or how city aliases are resolved.

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 the specific verb 'Retrieves' and names a clear resource: real-time transit service alerts, disruptions, construction advisories, and delays. This is distinct from sibling tools like get_departures or list_routes, though it does not explicitly call out those alternatives.

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?

No guidance is provided about when to use this tool versus alternatives such as get_departures or get_route_stops. The description states only what the tool retrieves, not the conditions or context that should lead an agent to choose it.

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?

No annotations are provided, so the description carries behavioral burden. It discloses that the tool lists routes and supports optional search filtering, but it does not explain behavior such as whether an unsupported city produces an error, how search filtering matches (substring vs exact), or what the response includes. This is acceptable for a simple read-only listing tool but not richly transparent.

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?

The description is a single, front-loaded sentence with no redundant wording. Every element — action, resource, scope, and filtering capability — 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?

For a low-complexity tool with two parameters and no output schema, the description provides enough to invoke it correctly: it lists routes for a city with optional search filtering. It could be slightly more complete by pointing to list_supported_cities for valid city identifiers or clarifying search matching, but these are minor gaps.

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 schema already documents both city and query parameters. The description adds only a generic reference to 'optional search filtering,' which adds no substantive meaning beyond the schema. The baseline of 3 applies because the schema carries the parameter documentation burden.

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 ('Lists'), a specific resource ('public transit routes/lines'), and a scope ('for a supported city'). It also mentions optional search filtering, making the tool's function clear. The resource type distinguishes it from sibling tools that deal with stops, departures, and service alerts.

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 phrase 'for a supported city' implies the caller should know whether a city is supported, but it does not explicitly point to list_supported_cities as the way to discover valid identifiers. No explicit when-to-use or when-not-to-use guidance is provided, though the intended use is reasonably inferable from the description.

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?

With no annotations provided, the description carries the full burden of behavioral disclosure. It accurately describes the content (cities, agencies, modes, capabilities) but does not mention the return format, whether the operation is read-only (though implied by 'lists'), or any potential pagination or limits. It covers the scope but lacks detail on output structure or edge cases.

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 that wastes no words. It leads with the core action and resource, and packall the key content into ~14 words. No redundancy or padding.

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 simple list tool with no parameters and no output schema, the description is nearly complete. It names all major categories of information returned (cities, agencies, modes, capabilities) and the scope (US transit). Minor gaps include the exact format of the response (e.g., list of objects vs. simple strings), but the description provides enough for an agent to invoke the tool without ambiguity.

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 has zero parameters, and the schema is an empty object, so there are no parameter semantics to document. The description does not need to elaborate on parameters, and the baseline for a zero-parameter tool is 4, which is appropriate here.

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 ('Lists') and names the exact resource ('supported US transit cities, transit agencies, modes, and feature capabilities'). It clearly differentiates from sibling tools like list_routes and get_departures, which target specific transit data rather than a broad catalog of supported locations and capabilities.

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?

Although the description does not explicitly state when to use this tool versus alternatives, the purpose itself implies it as a discovery tool—agents would call it before using sibling tools that require a city or agency context. No exclusions or conditions are provided, but the context is clear enough for an agent to infer its use case.

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