langfuse-mcp

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

With no annotations provided, the description carries the full burden and does well by disclosing key behavioral traits: it's a mutation tool (implied by 'Update'), labels are added and preserved (not replaced), labels are unique across versions, and the 'latest' label is managed externally by Langfuse. It lacks details on permissions, rate limits, or error handling, but covers essential operational context.

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 sized and front-loaded, with the first sentence stating the core purpose and subsequent sentences adding crucial context without waste. Every sentence earns its place by clarifying mutation scope, label behavior, and management 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's moderate complexity (mutation with 3 parameters), no annotations, and the presence of an output schema (which handles return values), the description is largely complete. It covers purpose, usage context, and key behaviors, but could improve by mentioning prerequisites like authentication or error scenarios, though the output schema mitigates some gaps.

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%, so the schema already documents all parameters (name, version, labels). The description adds minimal value beyond the schema by reiterating that labels are added and preserved, and labels are unique across versions, but does not provide additional syntax, format, or usage details for the parameters. Baseline 3 is appropriate as the schema does the heavy lifting.

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 specific action ('Update labels for a specific prompt version') with the resource ('prompt version'), distinguishing it from siblings like 'create_text_prompt' or 'get_prompt' which handle creation or retrieval rather than label updates. It explicitly mentions this is the only supported mutation for existing prompts, further differentiating its purpose.

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 clear context on when to use this tool ('the only supported mutation for existing prompts') and implies usage for adding labels to prompt versions. However, it does not explicitly state when not to use it or name specific alternatives among siblings, such as using 'create_text_prompt' for new prompts instead.

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