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MCP Kafka Schema Reg

count_contexts

Determine the total number of contexts within a Kafka Schema Registry using this tool, enabling efficient registry management and schema organization.

Instructions

Count the number of contexts in a registry.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
registryNo

Implementation Reference

  • Core implementation of the count_contexts tool handler. Uses registry client to fetch contexts, counts them, and returns structured JSON with metadata and error handling.
    @structured_output("count_contexts", fallback_on_error=True)
    def count_contexts_tool(registry_manager, registry_mode: str, registry: Optional[str] = None) -> Dict[str, Any]:
        """
        Count the number of contexts in a registry.
    
        Args:
            registry: Optional registry name (ignored in single-registry mode)
    
        Returns:
            Dictionary containing context count and details with registry metadata and structured validation
        """
        try:
            if registry_mode == "single":
                client = get_default_client(registry_manager)
            else:
                client = registry_manager.get_registry(registry)
                if client is None:
                    return create_error_response(
                        f"Registry '{registry}' not found",
                        error_code="REGISTRY_NOT_FOUND",
                        registry_mode=registry_mode,
                    )
    
            contexts = client.get_contexts()
            if isinstance(contexts, dict) and "error" in contexts:
                return create_error_response(
                    f"Failed to get contexts: {contexts.get('error')}",
                    error_code="CONTEXTS_RETRIEVAL_FAILED",
                    registry_mode=registry_mode,
                )
    
            # Get registry metadata
            metadata = client.get_server_metadata()
    
            result = {
                "registry": (client.config.name if hasattr(client.config, "name") else "default"),
                "count": len(contexts),
                "scope": "contexts",
                "contexts": contexts,
                "counted_at": datetime.now().isoformat(),
                "registry_mode": registry_mode,
                "mcp_protocol_version": "2025-06-18",
            }
    
            # Add metadata information, but preserve the scope field
            metadata_copy = metadata.copy()
            if "scope" in metadata_copy:
                # Preserve the simple string scope, but add server scope info separately
                metadata_copy["server_scope"] = metadata_copy.pop("scope")
            result.update(metadata_copy)
    
            return result
        except Exception as e:
            return create_error_response(str(e), error_code="CONTEXT_COUNT_FAILED", registry_mode=registry_mode)
  • JSON Schema definition (COUNT_SCHEMA) used for validating the structured output of the count_contexts tool.
    COUNT_SCHEMA = {
        "type": "object",
        "properties": {
            "count": {"type": "integer", "minimum": 0, "description": "Count result"},
            "scope": {
                "type": "string",
                "description": "What was counted (contexts, schemas, versions)",
            },
            "context": {
                "type": "string",
                "description": "Context name if scoped to context",
            },
            "registry": {"type": "string", "description": "Registry name"},
            **METADATA_FIELDS,
        },
        "required": ["count", "scope"],
        "additionalProperties": True,
    }
  • Mapping of the 'count_contexts' tool name to its output schema (COUNT_SCHEMA) in the TOOL_OUTPUT_SCHEMAS dictionary.
    "count_contexts": COUNT_SCHEMA,
  • Registration metadata for the count_contexts operation, specifying it as a QUICK direct operation (no task queue). Used for MCP client guidance.
    "count_contexts": {
        "duration": OperationDuration.QUICK,
        "pattern": AsyncPattern.DIRECT,
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool counts contexts, but doesn't explain key behaviors: whether it requires specific permissions, how it handles large registries (e.g., pagination or performance), what the output format is (e.g., integer count or structured response), or if there are any side effects. This leaves significant gaps for an AI agent to understand the tool's operation.

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?

The description is a single, clear sentence with no wasted words: 'Count the number of contexts in a registry.' It is front-loaded and efficiently conveys the core purpose without unnecessary elaboration, making it easy for an AI agent to parse quickly.

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

Completeness2/5

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

Given the lack of annotations, no output schema, and low schema description coverage (0%), the description is insufficiently complete. It doesn't address behavioral aspects like permissions, performance, or output format, nor does it provide usage context relative to siblings. For a tool that likely interacts with registries and contexts, more detail is needed to guide effective use.

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?

The input schema has one parameter ('registry') with 0% description coverage, meaning the schema provides no semantic details. The description mentions 'in a registry', implying the parameter specifies which registry to count contexts in, but doesn't clarify if it's optional (defaulting to a current registry) or required, or what values are valid. This adds minimal value beyond the schema's structure.

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

Purpose4/5

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

The description clearly states the tool's purpose: 'Count the number of contexts in a registry.' It specifies the verb ('Count') and resource ('contexts in a registry'), making the function unambiguous. However, it doesn't explicitly differentiate from sibling tools like 'list_contexts' or 'compare_contexts_across_registries', which might offer overlapping functionality.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives. With sibling tools like 'list_contexts' (which likely lists contexts) and 'compare_contexts_across_registries' (which might involve counting), there's no indication of when 'count_contexts' is preferred, such as for performance or summary purposes.

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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