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

Annotations already declare readOnly, idempotent, non-destructive, open-world behavior, so safety is covered. The description adds meaningful context beyond that: the tool surfaces a direct stream_url plus a listen_url for browser playback, and notes the data comes from a community directory. It does not discuss failure behavior for an unknown id, which keeps it from a 5.

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 first two sentences are tight and front-loaded with the retrieval purpose, the id source, and the useful return fields. The third sentence about broadcaster ownership and 72FM not curating stations is legal boilerplate that does not help an agent select or invoke the tool, so the description is somewhat larger than its job requires.

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?

An output schema exists, so return-value details are not strictly required, yet the description still names the key outputs (stream_url, listen_url) and the data source. For a one-parameter idempotent lookup this is nearly complete; only error/not-found behavior is unaddressed.

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% and the single parameter is documented with a UUID pattern, so the baseline is already met. The description goes further by clarifying the id is a Radio Browser stationuuid obtained from sibling tools, adding provenance the schema does not.

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 precise verb+resource: retrieve one radio station by its Radio Browser id. It also names the sibling tools that produce that id (search_stations, top_stations), so the agent can distinguish this lookup tool from the discovery tools without opening a schema.

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 tells the agent the id is 'as returned by search_stations or top_stations', which implies when this tool is the right follow-up call. It stops short of an explicit when-not-to-use statement, but the context is clear enough.

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, idempotentHint, openWorldHint and destructiveHint=false, so safety is covered. The description goes beyond that by disclosing the sort order (station count, highest first) and the fact that only countries with currently working stations are included, which is real behavioral context.

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 well-formed sentence that front-loads the scope (countries with stations) and closes with the ordering rule. No filler or redundancy.

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 need not explain return values, yet it usefully summarizes them anyhow. Scope, ordering, and the working-station filter are all covered; only when-to-use guidance against sibling tools is absent, which is a minor gap for a simple read-only listing.

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 limit and min_stations are fully documented in the schema itself. The description adds no syntax or format detail for either parameter, so the baseline 3 applies; the mention of station counts loosely relates to min_stations but adds no new semantics.

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?

Specific verb (List) plus resource (countries) with explicit scope: only countries that have internet radio stations in the directory. It also enumerates the payload (ISO 3166-1 alpha-2 codes, working-station counts, 72FM page), which distinguishes it from siblings like search_stations and list_genres that operate on different resources.

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 purpose implies a discovery/browse role, so an agent can infer this is the entry point for enumerating countries before filtering stations. However, it never states when to prefer this over siblings such as list_genres or search_stations, nor any prerequisite or exclusion. Usage is only implied.

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 readOnly/idempotent/non-destructive, so safety is covered. The description adds genuinely new behavioral context: results are ordered by count of working stations and placeholder/non-genre tags (country, region, language, 'radio', 'fm') are filtered out, which an agent could not infer from the 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?

Three tight sentences: purpose first, behavioral filtering second, routing guidance last. No filler, every sentence carries information an agent needs.

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?

A low-complexity, single-parameter read tool with full annotations and an output schema; the description covers purpose, filtering behavior, ordering, and the chaining target, leaving nothing material unexplained.

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% and the single limit parameter is fully documented in the schema (1-100, default 30). The description adds no further syntax or semantics for it, 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?

States a specific verb (List) and resource (genre/format tags in the Radio Browser directory) plus the ranking criterion (by number of working stations). The explicit filtering note distinguishes it from siblings like list_countries, which return the very country/region names this tool strips out.

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 gives explicit downstream usage — feed a returned name into search_stations or top_stations as the tag argument — which is strong contextual guidance. It stops short of stating when NOT to use it (e.g., use list_countries for country facets), so it is clear context without exclusions.

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 readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely non-structured behavior: broken streams are filtered out, results include stream URLs plus a browser listen_url, and the data provenance/licensing caveat. It does not mention rate limits or result stability, keeping it out of 5 territory.

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 core capability is front-loaded in the first sentence and the practical behavior (broken streams excluded, listen_url) follows. The final two sentences of provenance/ownership boilerplate are useful for trust but are not strictly about invocation, making it slightly longer than necessary.

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 need not detail return fields, and it correctly avoids that. Combined with 100% schema coverage and full annotation coverage, an agent has what it needs to call the tool, though filter-combination semantics and pagination/result-size behavior remain unstated.

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 all six parameters (tag, name, limit, order, language, countrycode) are already documented in the schema with examples and constraints. The description only restates the filter dimensions generically and adds no syntax, defaults, or combination semantics 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?

States a specific verb (Search) and resource (internet radio stations) plus the filter dimensions and the data source (Radio Browser community directory). It is immediately distinguishable from get_station and top_stations by implication, but never names or contrasts those siblings explicitly, which is what a 5 would require.

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 filter axes ('by name, genre tag, country and/or language') imply when the tool is useful, and the schema points to list_genres/list_countries for discovering valid values. However, there is no explicit when-to-use versus get_station or top_stations, no statement of how filters combine (AND vs OR), and no guidance on empty results.

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 readOnly/idempotent/openWorld/destructive=false, so the safety profile is covered. The description adds real behavioral value: broken streams are excluded, results come from the Radio Browser community directory, and ranking options are explained. This goes beyond what annotations provide.

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?

Purpose and ranking modes are front-loaded in the first sentence, and filtering and exclusion behavior follow logically. The closing sentences on data provenance and broadcaster ownership are somewhat tangential to tool selection, but the overall structure remains tight and readable.

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-value explanation is unnecessary, and the description covers ranking semantics, optional filters, and stream-quality behavior. An agent has enough to invoke it correctly; only explicit sibling routing is missing.

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 all four parameters (by, tag, limit, countrycode) are already documented in the schema, including the enum meanings and ISO code pattern. The description restates the optional country/genre filtering without adding syntax or format detail beyond the schema, 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?

States a specific verb+resource ('List the most popular internet radio stations') and enumerates the three ranking modes. It is clearly distinguishable from siblings like search_stations and get_station, which would serve different intents.

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 when to use it (to browse popularity-ranked stations) and clarifies the three ranking modes, but it never names an alternative such as search_stations or states when this tool is the wrong choice. Usage is inferable rather than explicit.

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