get_term_ancestors
Retrieve parent terms from biological ontologies using term IRI and ontology identifier to understand hierarchical relationships in OLS MCP Server.
Instructions
Get ancestor terms (parents) of a specific term.
Args: term_iri: The IRI of the term ontology: The ontology identifier include_obsolete: Include obsolete entities size: Maximum number of results
Returns: JSON formatted list of ancestor terms
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| term_iri | Yes | ||
| ontology | Yes | ||
| include_obsolete | No | ||
| size | No |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Implementation Reference
- src/ols_mcp_server/server.py:219-254 (handler)The core handler function for the 'get_term_ancestors' tool. It is decorated with @mcp.tool() which also serves as registration. Queries the OLS API for ancestor terms of a given term IRI in a specific ontology, formats the response, and handles errors.
@mcp.tool() async def get_term_ancestors( term_iri: str, ontology: str, include_obsolete: bool = False, size: int = 20 ) -> str: """Get ancestor terms (parents) of a specific term. Args: term_iri: The IRI of the term ontology: The ontology identifier include_obsolete: Include obsolete entities size: Maximum number of results Returns: JSON formatted list of ancestor terms """ encoded_iri = url_encode_iri(term_iri) params: dict[str, Any] = { "page": 0, "size": size, "includeObsoleteEntities": include_obsolete } url = f"{OLS_BASE_URL}/api/v2/ontologies/{ontology}/classes/{encoded_iri}/ancestors" try: response = await client.get(url, params=params) response.raise_for_status() data = response.json() return format_response(data, size) except httpx.HTTPError as e: return f"Error getting term ancestors: {str(e)}" - src/ols_mcp_server/server.py:219-219 (registration)Registration of the 'get_term_ancestors' tool using FastMCP's @mcp.tool() decorator.
@mcp.tool() - src/ols_mcp_server/server.py:30-65 (helper)Helper function used by get_term_ancestors to format the API response into a readable JSON structure.
def format_response(data: Any, max_items: int = 10) -> str: """Format API response data for display.""" if isinstance(data, dict): if "elements" in data: # Handle paginated response elements = data["elements"][:max_items] total = data.get("totalElements", len(elements)) result = [] for item in elements: if isinstance(item, dict): # Extract key fields for display label = item.get("label", "") iri = item.get("iri", "") description = item.get("description", []) if isinstance(description, list) and description: description = description[0] elif isinstance(description, list): description = "" result.append({ "label": label, "iri": iri, "description": description[:200] + "..." if len(str(description)) > 200 else description }) return json.dumps({ "items": result, "total_items": total, "showing": len(result) }, indent=2) else: # Single item response return json.dumps(data, indent=2) return json.dumps(data, indent=2) - src/ols_mcp_server/server.py:25-27 (helper)Helper function used to double URL encode the term IRI for OLS API requests.
def url_encode_iri(iri: str) -> str: """Double URL encode an IRI as required by OLS API.""" return urllib.parse.quote(urllib.parse.quote(iri, safe=""), safe="")