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clinicaltrialsgov-mcp-server

by io.github.cyanheads
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Clinicaltrials Get Study Count

clinicaltrials_get_study_count
Read-onlyIdempotent

Get total clinical trial study count from ClinicalTrials.gov matching a query, without fetching study data. Fast and lightweight. Use for quick statistics or to build breakdowns by calling multiple times with different filters (e.g., count by phase, count by status, count recruiting vs completed for a condition).

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
queryNoGeneral free-text search across all fields. Runs the 57-field relevance search ClinicalTrials.gov publishes for this parameter — NCTId, NCTIdAlias, OrgStudyId, SecondaryId, Acronym, BriefTitle, OfficialTitle, Condition, InterventionName, InterventionOtherName, Phase, StdAge, StudyType, BriefSummary, outcome measures and their descriptions, LeadSponsorName, CollaboratorName, the Location* fields, the Design* fields, and the ConditionAncestorTerm/InterventionAncestorTerm MeSH umbrellas — so a hit need not carry your term in the field you had in mind. Plain words plus AND, OR, NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression — those work here as well as in advancedFilter, so AREA[Phase]PHASE2 is accepted in this parameter; a stray bracket fails. `( )` group sub-expressions and work when matched; `,` acts as AND. The dedicated *Query parameters (conditionQuery, interventionQuery, etc.) scope a search to one field.
titleQueryNoSearch within study titles and acronyms only. Matches Acronym, BriefTitle, and OfficialTitle. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
phaseFilterNoFilter by trial phase. Omit to count all phases — an empty list is rejected, not treated as "no filter". Values: EARLY_PHASE1, PHASE1, PHASE2, PHASE3, PHASE4, NA.
outcomeQueryNoSearch within outcome measure fields. Matches PrimaryOutcomeMeasure, SecondaryOutcomeMeasure, OtherOutcomeMeasure, and OutcomeMeasureTitle, plus their description counterparts PrimaryOutcomeDescription, SecondaryOutcomeDescription, OtherOutcomeDescription, OutcomeMeasureDescription, and OutcomeMeasurePopulationDescription — so a term appearing only in outcome prose still matches. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
sponsorQueryNoSponsor/collaborator name search. Matches LeadSponsorName, CollaboratorName, and OrgFullName. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
statusFilterNoFilter by study status. Omit to count all statuses — an empty list is rejected, not treated as "no filter". Values: RECRUITING, COMPLETED, ACTIVE_NOT_RECRUITING, NOT_YET_RECRUITING, ENROLLING_BY_INVITATION, SUSPENDED, TERMINATED, WITHDRAWN, UNKNOWN, WITHHELD, NO_LONGER_AVAILABLE, AVAILABLE, APPROVED_FOR_MARKETING, TEMPORARILY_NOT_AVAILABLE.
locationQueryNoLocation search — city, state, country, or facility name. Matches LocationCity, LocationState, LocationCountry, LocationFacility, and LocationZip; a study matches when any of its sites does. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
advancedFilterNoAdvanced filter using AREA[FieldName]value syntax. Examples: "AREA[StudyType]INTERVENTIONAL", "AREA[EnrollmentCount]RANGE[100, 1000]", "AREA[Phase]PHASE2 AND AREA[StudyType]INTERVENTIONAL", "(AREA[Phase]PHASE3 OR AREA[Phase]PHASE4) AND AREA[StudyType]INTERVENTIONAL". AND/OR/NOT join complete AREA[FieldName]value expressions; parentheses group them. Call clinicaltrials_get_field_definitions to find AREA[]-compatible field names.
conditionQueryNoCondition/disease-specific search. E.g., "Type 2 Diabetes", "non-small cell lung cancer". Matches Condition, BriefTitle, OfficialTitle, ConditionMeshTerm, ConditionAncestorTerm, Keyword, and NCTId. ConditionAncestorTerm is the MeSH umbrella above the conditions a study itself lists, so results run broader than those lists — a study can match a parent term it never names. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
interventionQueryNoIntervention/treatment search. E.g., "pembrolizumab", "cognitive behavioral therapy". Matches InterventionName, InterventionType, ArmGroupType, InterventionOtherName, BriefTitle, OfficialTitle, ArmGroupLabel, InterventionMeshTerm, Keyword, InterventionAncestorTerm, InterventionDescription, and ArmGroupDescription. InterventionAncestorTerm is the MeSH umbrella above the interventions a study itself lists, so results run broader than those lists. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND.
includeUnknownEnrollmentNoInclude studies whose EnrollmentCount is the upstream "unknown" sentinel (99999999). Excluded by default — the sentinel pollutes RANGE[N, MAX] queries. Set true for data-quality audits.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
errorNoPresent when the call failed. Absent on success.
noticeNoRecovery guidance when totalCount is 0 — suggests how to broaden the query or filters.
totalCountNoTotal studies matching the query/filters.
searchCriteriaNoEcho of active query/filter criteria applied to this count, including sentinelFilterActive when the default unknown-enrollment exclusion is in effect.

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed6 schema fields changed
    • changedInput schema / $schema
      Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • addedInput schema / additionalProperties
      Added value: +false
    • changedOutput schema / $schema
      Previous value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"
    • addedOutput schema / anyOf
      Added value: +[
+  {
+    "not": {
+      "required": [
+        "error"
+      ]
+    },
+    "required": [
+      "totalCount"
+    ]
+  },
+  {
+    "required": [
+      "error"
+    ]
+  }
+]
    • addedOutput schema / properties / error
      Added value: +{
+  "additionalProperties": {},
+  "description": "Present when the call failed. Absent on success.",
+  "properties": {
+    "code": {
+      "description": "JSON-RPC error code for this failure.",
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    "data": {
+      "additionalProperties": {},
+      "properties": {
+        "reason": {
+          "description": "Machine-readable failure mode. Declared by this tool: `blank_value`: A parameter was supplied with a blank, whitespace-only, or empty-list value. `field_invalid`: A field name in the advanced filter or AREA[] expression is invalid (often a module name instead of a piece name). `enum_invalid`: statusFilter or phaseFilter contains a value ClinicalTrials.gov does not accept. `query_parse_error`: A free-text query or advancedFilter expression uses syntax the upstream Essie parser rejects — typically a `[` or `]` outside an AREA[…] / RANGE[…] expression, an unmatched `(` / `)`, or an unterminated quote in a query/conditionQuery/etc. value. `rate_limited`: ClinicalTrials.gov returned 429 after retry budget exhausted. Other values are possible when a failure originates below the handler.",
+          "examples": [
+            "blank_value",
+            "field_invalid",
+            "enum_invalid",
+            "query_parse_error",
+            "rate_limited"
+          ],
+          "type": "string"
+        },
+        "recovery": {
+          "additionalProperties": {},
+          "description": "Actionable next step for the caller.",
+          "properties": {
+            "hint": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "hint"
+          ],
+          "type": "object"
+        },
+        "retryable": {
+          "description": "Whether retrying may succeed.",
+          "type": "boolean"
+        }
+      },
+      "type": "object"
+    },
+    "message": {
+      "description": "Human-readable description of what went wrong.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "code",
+    "message"
+  ],
+  "type": "object"
+}
    • removedOutput schema / required
      Removed value: -[
-  "totalCount"
-]
  2. Changed9 schema fields changed
    • changedInput schema / properties / conditionQuery / description
      Previous value: -"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Matches Condition, BriefTitle, OfficialTitle, ConditionMeshTerm, ConditionAncestorTerm, Keyword, and NCTId. ConditionAncestorTerm is the MeSH umbrella above the conditions a study itself lists, so results run broader than those lists — a study can match a parent term it never names. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / interventionQuery / description
      Previous value: -"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Matches InterventionName, InterventionType, ArmGroupType, InterventionOtherName, BriefTitle, OfficialTitle, ArmGroupLabel, InterventionMeshTerm, Keyword, InterventionAncestorTerm, InterventionDescription, and ArmGroupDescription. InterventionAncestorTerm is the MeSH umbrella above the interventions a study itself lists, so results run broader than those lists. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / locationQuery / description
      Previous value: -"Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Location search — city, state, country, or facility name. Matches LocationCity, LocationState, LocationCountry, LocationFacility, and LocationZip; a study matches when any of its sites does. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / outcomeQuery / description
      Previous value: -"Search within outcome measure fields. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Search within outcome measure fields. Matches PrimaryOutcomeMeasure, SecondaryOutcomeMeasure, OtherOutcomeMeasure, and OutcomeMeasureTitle, plus their description counterparts PrimaryOutcomeDescription, SecondaryOutcomeDescription, OtherOutcomeDescription, OutcomeMeasureDescription, and OutcomeMeasurePopulationDescription — so a term appearing only in outcome prose still matches. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / phaseFilter / anyOf
      Previous value: -[
-  {
-    "description": "A single phase value.",
-    "type": "string"
-  },
-  {
-    "description": "Multiple phase values (OR).",
-    "items": {
-      "type": "string"
-    },
-    "minItems": 1,
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single phase value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple phase values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  }
+]
    • changedInput schema / properties / query / description
      Previous value: -"General free-text search across all fields. Plain words plus AND, OR, NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression — those work here as well as in advancedFilter, so AREA[Phase]PHASE2 is accepted in this parameter; a stray bracket fails. `( )` group sub-expressions and work when matched; `,` acts as AND. The dedicated *Query parameters (conditionQuery, interventionQuery, etc.) scope a search to one field."New value: +"General free-text search across all fields. Runs the 57-field relevance search ClinicalTrials.gov publishes for this parameter — NCTId, NCTIdAlias, OrgStudyId, SecondaryId, Acronym, BriefTitle, OfficialTitle, Condition, InterventionName, InterventionOtherName, Phase, StdAge, StudyType, BriefSummary, outcome measures and their descriptions, LeadSponsorName, CollaboratorName, the Location* fields, the Design* fields, and the ConditionAncestorTerm/InterventionAncestorTerm MeSH umbrellas — so a hit need not carry your term in the field you had in mind. Plain words plus AND, OR, NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression — those work here as well as in advancedFilter, so AREA[Phase]PHASE2 is accepted in this parameter; a stray bracket fails. `( )` group sub-expressions and work when matched; `,` acts as AND. The dedicated *Query parameters (conditionQuery, interventionQuery, etc.) scope a search to one field."
    • changedInput schema / properties / sponsorQuery / description
      Previous value: -"Sponsor/collaborator name search. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Sponsor/collaborator name search. Matches LeadSponsorName, CollaboratorName, and OrgFullName. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / statusFilter / anyOf
      Previous value: -[
-  {
-    "description": "A single status value.",
-    "type": "string"
-  },
-  {
-    "description": "Multiple status values (OR).",
-    "items": {
-      "type": "string"
-    },
-    "minItems": 1,
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single status value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple status values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  }
+]
    • changedInput schema / properties / titleQuery / description
      Previous value: -"Search within study titles and acronyms only. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Search within study titles and acronyms only. Matches Acronym, BriefTitle, and OfficialTitle. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
  3. Changed4 schema fields changed
    • changedInput schema / properties / phaseFilter / anyOf
      Previous value: -[
-  {
-    "description": "A single phase value.",
-    "type": "string"
-  },
-  {
-    "description": "Multiple phase values (OR).",
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single phase value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple phase values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "minItems": 1,
+    "type": "array"
+  }
+]
    • changedInput schema / properties / phaseFilter / description
      Previous value: -"Filter by trial phase. Values: EARLY_PHASE1, PHASE1, PHASE2, PHASE3, PHASE4, NA."New value: +"Filter by trial phase. Omit to count all phases — an empty list is rejected, not treated as \"no filter\". Values: EARLY_PHASE1, PHASE1, PHASE2, PHASE3, PHASE4, NA."
    • changedInput schema / properties / statusFilter / anyOf
      Previous value: -[
-  {
-    "description": "A single status value.",
-    "type": "string"
-  },
-  {
-    "description": "Multiple status values (OR).",
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single status value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple status values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "minItems": 1,
+    "type": "array"
+  }
+]
    • changedInput schema / properties / statusFilter / description
      Previous value: -"Filter by study status. Values: RECRUITING, COMPLETED, ACTIVE_NOT_RECRUITING, NOT_YET_RECRUITING, ENROLLING_BY_INVITATION, SUSPENDED, TERMINATED, WITHDRAWN, UNKNOWN, WITHHELD, NO_LONGER_AVAILABLE, AVAILABLE, APPROVED_FOR_MARKETING, TEMPORARILY_NOT_AVAILABLE."New value: +"Filter by study status. Omit to count all statuses — an empty list is rejected, not treated as \"no filter\". Values: RECRUITING, COMPLETED, ACTIVE_NOT_RECRUITING, NOT_YET_RECRUITING, ENROLLING_BY_INVITATION, SUSPENDED, TERMINATED, WITHDRAWN, UNKNOWN, WITHHELD, NO_LONGER_AVAILABLE, AVAILABLE, APPROVED_FOR_MARKETING, TEMPORARILY_NOT_AVAILABLE."
  4. Changed7 schema fields changed
    • changedInput schema / properties / conditionQuery / description
      Previous value: -"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / interventionQuery / description
      Previous value: -"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / locationQuery / description
      Previous value: -"Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / outcomeQuery / description
      Previous value: -"Search within outcome measure fields. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Search within outcome measure fields. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / query / description
      Previous value: -"General free-text search across all fields. Plain words plus AND, OR, NOT. `[ ]` are reserved (advancedFilter AREA[] only); `( )` group sub-expressions and work when matched; `,` acts as AND. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."New value: +"General free-text search across all fields. Plain words plus AND, OR, NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression — those work here as well as in advancedFilter, so AREA[Phase]PHASE2 is accepted in this parameter; a stray bracket fails. `( )` group sub-expressions and work when matched; `,` acts as AND. The dedicated *Query parameters (conditionQuery, interventionQuery, etc.) scope a search to one field."
    • changedInput schema / properties / sponsorQuery / description
      Previous value: -"Sponsor/collaborator name search. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Sponsor/collaborator name search. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / titleQuery / description
      Previous value: -"Search within study titles and acronyms only. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."New value: +"Search within study titles and acronyms only. Plain words plus AND/OR/NOT. `[ ]` are valid only inside an AREA[FieldName]value or RANGE[min, max] expression, which this parameter accepts; a stray bracket fails. `( )` group sub-expressions when matched; `,` acts as AND."
  5. Changed1 schema field changed
    • changedOutput schema / properties / searchCriteria / description
      Previous value: -"Echo of active query/filter criteria applied to this count."New value: +"Echo of active query/filter criteria applied to this count, including sentinelFilterActive when the default unknown-enrollment exclusion is in effect."
  6. Changed7 schema fields changed
    • changedInput schema / properties / conditionQuery / description
      Previous value: -"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / interventionQuery / description
      Previous value: -"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / locationQuery / description
      Previous value: -"Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / outcomeQuery / description
      Previous value: -"Search within outcome measure fields. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Search within outcome measure fields. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / query / description
      Previous value: -"General free-text search across all fields. Plain words plus AND, OR, NOT only — reserved chars `[ ] ( ) ,` will fail. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."New value: +"General free-text search across all fields. Plain words plus AND, OR, NOT. `[ ]` are reserved (advancedFilter AREA[] only); `( )` group sub-expressions and work when matched; `,` acts as AND. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."
    • changedInput schema / properties / sponsorQuery / description
      Previous value: -"Sponsor/collaborator name search. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Sponsor/collaborator name search. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
    • changedInput schema / properties / titleQuery / description
      Previous value: -"Search within study titles and acronyms only. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"New value: +"Search within study titles and acronyms only. Plain words plus AND/OR/NOT. `[ ]` are reserved; `( )` group sub-expressions when matched; `,` acts as AND."
  7. Changed3 schema fields changed
    • addedInput schema / properties / locationQuery
      Added value: +{
+  "description": "Location search — city, state, country, or facility name. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,",
+  "type": "string"
+}
    • addedInput schema / properties / outcomeQuery
      Added value: +{
+  "description": "Search within outcome measure fields. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,",
+  "type": "string"
+}
    • addedInput schema / properties / titleQuery
      Added value: +{
+  "description": "Search within study titles and acronyms only. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,",
+  "type": "string"
+}
  8. Changed3 schema fields changed
    • removedOutput schema / properties / noMatchHints
      Removed value: -{
-  "description": "Suggestions when no studies match (totalCount is 0).",
-  "items": {
-    "type": "string"
-  },
-  "type": "array"
-}
    • addedOutput schema / properties / notice
      Added value: +{
+  "description": "Recovery guidance when totalCount is 0 — suggests how to broaden the query or filters.",
+  "type": "string"
+}
    • changedOutput schema / properties / searchCriteria / description
      Previous value: -"Echo of query/filter criteria used."New value: +"Echo of active query/filter criteria applied to this count."
  9. Changed1 schema field changed
    • changedInput schema / properties / advancedFilter / description
      Previous value: -"Advanced filter using AREA[] syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses. Use clinicaltrials_get_field_definitions with a query to find AREA[]-compatible field names."New value: +"Advanced filter using AREA[FieldName]value syntax. Examples: \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\", \"AREA[Phase]PHASE2 AND AREA[StudyType]INTERVENTIONAL\", \"(AREA[Phase]PHASE3 OR AREA[Phase]PHASE4) AND AREA[StudyType]INTERVENTIONAL\". AND/OR/NOT join complete AREA[FieldName]value expressions; parentheses group them. Call clinicaltrials_get_field_definitions to find AREA[]-compatible field names."
  10. Changed2 schema fields changed
    • changedInput schema / properties / advancedFilter / description
      Previous value: -"Advanced filter using AREA[] Essie syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses. Use clinicaltrials_get_field_definitions with a query to find AREA[]-compatible field names."New value: +"Advanced filter using AREA[] syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses. Use clinicaltrials_get_field_definitions with a query to find AREA[]-compatible field names."
    • changedInput schema / properties / query / description
      Previous value: -"General free-text search across all fields. Plain words plus AND, OR, NOT only — brackets, parentheses, and commas are reserved by the upstream Essie parser and will fail. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."New value: +"General free-text search across all fields. Plain words plus AND, OR, NOT only — reserved chars `[ ] ( ) ,` will fail. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."
  11. Changed4 schema fields changed
    • changedInput schema / properties / conditionQuery / description
      Previous value: -"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\"."New value: +"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\". Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"
    • changedInput schema / properties / interventionQuery / description
      Previous value: -"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\"."New value: +"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\". Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"
    • changedInput schema / properties / query / description
      Previous value: -"General full-text search across all fields."New value: +"General free-text search across all fields. Plain words plus AND, OR, NOT only — brackets, parentheses, and commas are reserved by the upstream Essie parser and will fail. For field-scoped searches, use the dedicated *Query parameters (conditionQuery, interventionQuery, etc.) or advancedFilter with AREA[FieldName]value."
    • changedInput schema / properties / sponsorQuery / description
      Previous value: -"Sponsor/collaborator name search."New value: +"Sponsor/collaborator name search. Plain words plus AND/OR/NOT only — reserved chars: [ ] ( ) ,"
  12. Changed1 schema field changed
    • addedInput schema / properties / includeUnknownEnrollment
      Added value: +{
+  "default": false,
+  "description": "Include studies whose EnrollmentCount is the upstream \"unknown\" sentinel (99999999). Excluded by default — the sentinel pollutes RANGE[N, MAX] queries. Set true for data-quality audits.",
+  "type": "boolean"
+}
  13. Changed1 schema field changed
    • changedInput schema / properties / advancedFilter / description
      Previous value: -"Advanced filter using AREA[] Essie syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses."New value: +"Advanced filter using AREA[] Essie syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses. Use clinicaltrials_get_field_definitions with a query to find AREA[]-compatible field names."
  14. Changed2 schema fields changed
    • changedInput schema / properties / phaseFilter / anyOf
      Previous value: -[
-  {
-    "type": "string"
-  },
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single phase value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple phase values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  }
+]
    • changedInput schema / properties / statusFilter / anyOf
      Previous value: -[
-  {
-    "type": "string"
-  },
-  {
-    "items": {
-      "type": "string"
-    },
-    "type": "array"
-  }
-]New value: +[
+  {
+    "description": "A single status value.",
+    "type": "string"
+  },
+  {
+    "description": "Multiple status values (OR).",
+    "items": {
+      "type": "string"
+    },
+    "type": "array"
+  }
+]
  15. Changed5 schema fields changed
    • changedInput schema / properties / advancedFilter / description
      Previous value: -"Advanced AREA[] filter expression."New value: +"Advanced filter using AREA[] Essie syntax. E.g., \"AREA[StudyType]INTERVENTIONAL\", \"AREA[EnrollmentCount]RANGE[100, 1000]\". Combine with AND/OR/NOT and parentheses."
    • changedInput schema / properties / conditionQuery / description
      Previous value: -"Condition/disease search."New value: +"Condition/disease-specific search. E.g., \"Type 2 Diabetes\", \"non-small cell lung cancer\"."
    • changedInput schema / properties / interventionQuery / description
      Previous value: -"Intervention/treatment search."New value: +"Intervention/treatment search. E.g., \"pembrolizumab\", \"cognitive behavioral therapy\"."
    • changedInput schema / properties / query / description
      Previous value: -"General full-text search."New value: +"General full-text search across all fields."
    • changedInput schema / properties / sponsorQuery / description
      Previous value: -"Sponsor search."New value: +"Sponsor/collaborator name search."
  16. First observed

TDQS

A4.2/5.0
Behavior4/5

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint. The description adds behavioral value by noting it is 'Fast and lightweight' and 'without fetching study data,' and by suggesting repeated calls with different filters, which reinforces safe, side-effect-free usage. 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.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three sentences with no filler. The core purpose is front-loaded, followed by concrete use cases. Every sentence earns its place, and the description is appropriately sized for the tool's simplicity.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness4/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's complexity (11 optional parameters), the rich schema descriptions, and the presence of an output schema, the description is largely complete. It covers the main use cases and distinguishes the tool from siblings. It does not explicitly mention that calling with no filters returns the overall total, but the schema's optional parameters and the phrase 'matching a query' make that inferable.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

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 all 11 parameters in detail. The description adds only high-level examples of filters ('phase, status, condition') that map to existing parameters, but no new semantic meaning beyond the schema. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource: 'Get total clinical trial study count from ClinicalTrials.gov matching a query.' It also distinguishes itself from sibling tools by explicitly saying 'without fetching study data,' which separates it from search/record tools. The use-case framing ('quick statistics', 'breakdowns') further clarifies its unique role.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context for when to use it: 'Use for quick statistics or to build breakdowns by calling multiple times with different filters.' It implies the alternative (fetching study data) is not this tool's purpose, but it does not explicitly name sibling tools or state when not to use it. This is clear guidance with no exclusions, but not fully explicit.

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

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