langfuse-mcp-java

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

The description adds valuable behavioral context beyond annotations: it discloses the side effect of creating/updating the parent dataset run, and notes the JSON validation requirement for metadataJson. Annotations indicate destructiveHint=true, which aligns with the 'Creates' action. However, the description contradicts the input schema regarding parameter optionality, which could mislead the agent about invocation requirements.

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 description is appropriately concise with three sentences that are front-loaded (purpose first, then constraints). Each sentence earns its place without redundancy. Minor structural issue: the second sentence jams two field requirements together with 'and' while the third covers three different constraints.

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?

Given the tool has 8 parameters (all marked required in schema), destructive annotations, and complex side effects (upserting parent run), the description covers the main behavioral intent but is compromised by incorrect parameter requirement documentation. With no output schema, the description appropriately focuses on input requirements, but the contradictions make it incomplete.

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 description actively contradicts the input schema for 6 of 8 parameters: it states traceId is 'strongly recommended' and observationId is 'optional,' while the schema marks them as required. Similarly, it implies metadataJson is optional ('when provided'), but the schema requires it. While it adds the JSON validation constraint, the misinformation about requirement status is critical.

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?

The description clearly states the tool 'Creates a dataset run item' (specific verb + resource) and adds the side effect that it 'creates or updates the dataset run if needed.' While it distinguishes from sibling tools like create_dataset via the resource name, it does not explicitly clarify when to use this versus create_dataset_item.

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 provides guidance on field importance (runName/datasetItemId 'required', traceId 'strongly recommended', observationId 'optional'), which helps with invocation. However, it lacks explicit guidance on when to use this tool versus siblings like create_dataset_item or add_item_to_dataset, and mentions no prerequisites.

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