US fertility and IVF clinics from the CDC's public data.
Scored across 6 tools
Each tool targets a distinct resource or operation: get_listing retrieves a single clinic by slug, search_listings searches by text/place/category, list_categories/list_places/list_sources enumerate facets, and get_stats provides aggregate counts. No two tools overlap in purpose.
All tool names follow a consistent verb_noun snake_case pattern (get_listing, get_stats, list_categories, list_places, list_sources, search_listings). The minor singular/plural difference (listing vs listings) is negligible and typical.
Six tools are well-scoped for a read-only directory API: one retrieval, one search, three facet lists, and one stats endpoint. No tool feels redundant or missing from the core set.
The surface covers single retrieval, search, facet exploration, source metadata, and statistics. However, there is no explicit tool to list all clinics without a search query, which could hinder browsing; search_listings may or may not support empty queries.
Get one published fertility clinic by its slug.
| Name | Required | Description | Default |
|---|---|---|---|
| slug | Yes | The listing slug. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds one genuinely useful behavioral fact, that only published listings are retrievable, but says nothing about behavior for an unpublished or missing slug. That is adequate, not rich.
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 twelve-word sentence with the verb, scope and lookup key front-loaded. Nothing is wasted and nothing is buried.
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-parameter lookup this is close to sufficient, and annotations carry the safety profile. However, with no output schema the description does not indicate what a listing record contains, nor what happens on a miss, leaving an agent to infer the failure mode.
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?
Single parameter with 100% schema description coverage, so the schema already documents the slug, its pattern and length bounds. 'By its slug' adds no format or resolution detail beyond the schema, making the baseline 3 correct.
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 one published fertility clinic') plus the lookup key ('by its slug'). The 'one' and 'by slug' framing implicitly separates it from search_listings, but no sibling is named, so it falls short of a 5.
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?
There is no when-to-use guidance and no mention of alternatives. An agent holding a partial name rather than a slug is never pointed at search_listings, and no prerequisite for obtaining a slug is stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Get the number of published fertility clinics, places and categories, and when the data last changed.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds real behavioral context beyond that: the counts cover only 'published' clinics (a scoping filter) and the response reflects 'when the data last changed', which tells the agent about data freshness.
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 sentence that front-loads the core action and lists the returned metrics compactly. No filler, no repetition of the tool name, and nothing extraneous to trim.
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 zero-parameter, read-only stats tool with no output schema, the description adequately conveys the returned quantities and the freshness indicator. A minor gap remains: it doesn't specify the format of the 'last changed' value or the shape of the counts, which matters somewhat given there is no output schema.
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 per the rubric the baseline is 4. There is no parameter behavior to explain, and the description correctly focuses on what the call returns rather than inventing input 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?
States a specific verb ('Get the number of') and precisely names the resources counted: published fertility clinics, places, and categories, plus the last-changed timestamp. This aggregate-count purpose is unmistakably distinct from the sibling list_*/search_* tools, so an agent can select it without opening any 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?
Usage is implied rather than stated: the description makes clear this is for aggregate counts and data-freshness, not for retrieving individual records. However, it never says when to prefer this over list_categories/list_places or search_listings, and gives no exclusions or prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
List categories with their fertility clinic counts.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds one piece of behavioral context – that the response pairs each category with a clinic count – but says nothing about ordering, pagination, or refresh behavior.
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; every word carries information.
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 still conveys the return shape (categories plus clinic counts). For a trivial zero-parameter read tool this is nearly complete, though a note on whether the list is exhaustive would close the last gap.
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 the schema-baseline is 4 and there is no parameter semantics for the description to compensate for.
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 ('List categories') and adds the payload detail that each category comes with a fertility clinic count. It is clearly distinct from siblings like get_stats or list_places, though it never explicitly contrasts itself with them.
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?
There is no guidance on when to choose this over get_stats, list_places, or list_sources, nor any prerequisite or exclusion noted. Usage is only implied by the resource name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
List countries, regions and cities that have fertility clinics.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds only the notion of filtering by clinic presence, with no note on ordering, grouping, or completeness of the returned list.
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 zero filler. Every word earns its place and the resource scope is stated immediately.
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 zero-parameter, read-only listing tool with no output schema and full annotation coverage, the description is nearly sufficient. It could optionally indicate the geographic hierarchy or ordering of results, but nothing essential 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?
The tool takes zero parameters, so per the rubric the baseline is 4. The description adds no parameter context, which is appropriate here since the schema has none.
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 ("countries, regions and cities") with clear scope (those that have fertility clinics). It is distinguishable from siblings like get_stats or search_listings, but it does not explicitly contrast itself with the other list_* tools.
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?
There is no statement of when to use this tool versus list_categories, list_sources, or search_listings. The agent must infer usage purely from the name and the single descriptive sentence.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
List where the fertility clinic data comes from, with the license and refresh of each source.
| Name | Required | Description | Default |
|---|---|---|---|
No parameters | |||
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description's only added behavioral value is naming the returned fields (license, refresh); it says nothing about ordering, caching, or pagination.
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 sentence with no filler; the resource and the returned attributes are front-loaded and every clause carries information.
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 parameters and no output schema, the description must carry the return-value burden, and it does by naming license and refresh per source. It is adequate for a trivial read-only listing, though it omits any hint of result shape or count.
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 the baseline is 4. There is no parameter surface for the description to explain, and nothing is misrepresented.
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 a clearly bounded resource (the fertility clinic data sources), plus the attributes returned (license, refresh). The resource is distinct from siblings like list_categories and list_places, so an agent can tell them apart, though the description never explicitly contrasts itself with them.
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 usage (call this to learn where the data originates and how fresh it is), but there is no explicit when-to-use statement, no prerequisites, and no mention of alternatives such as get_stats or get_listing. Usage must be inferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Search published fertility clinics by text, place and category.
| Name | Required | Description | Default |
|---|---|---|---|
| q | No | Search text, with at least one letter or digit. Matches name, categories, attributes, description and place. Typos fall back to close matches. | |
| city | No | City slug, from /places. | |
| sort | No | `relevance` needs `q` and is the default with it. `name` is the default without `q`. `recent` is newest first. | |
| limit | No | Items per page. | |
| cursor | No | `page.nextCursor` from the previous response. Opaque. Send the same filters and `limit`. | |
| region | No | Region slug, from /places. | |
| country | No | ISO 3166-1 alpha-2 country code, any case. A country the directory does not cover, as listed in /places, gives 400. | |
| category | No | Category slug, from /categories. A parent slug also matches its children. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the safety profile is covered. The description's one extra behavioral fact is that only "published" clinics are searchable, which is useful scoping context but does not address pagination, result caps, or rate limits.
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 with the resource and scope front-loaded and no filler. It is appropriately terse, though it is thin enough that it reads more like a label than a full definition.
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 an 8-parameter, paginated search tool with no output schema, the description leaves the agent without any hint of the response shape, paging model, or empty-result behavior; the schema compensates for the inputs but not the outputs.
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% across all 8 parameters, including sort defaults, cursor chaining, and slug sources, so the schema does the heavy lifting. The description only loosely maps its facet phrase (text/place/category) onto q, city/region/country, and category, adding little 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?
States a specific verb ("Search") and resource ("published fertility clinics") plus the three facet axes (text, place, category), which is enough for an agent to know what it returns. It does not distinguish itself from siblings such as get_listing or list_places, so it stops short of a 5.
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?
There is no when-to-use guidance, no prerequisites, and no routing to alternatives. The fact that city/region/category slugs must first come from /places and /categories appears only in the schema parameter descriptions, not in the tool description.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
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