Happy Server MCP

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

No annotations are provided, so the description carries full burden. It states the tool performs a linking operation, implying a mutation, but doesn't disclose behavioral traits such as permissions required, whether the link is reversible, error handling, or side effects. For a mutation tool with zero annotation coverage, this is a significant gap in transparency.

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 a single, efficient sentence that front-loads the core action. It avoids unnecessary words and directly states the purpose. However, it could be slightly more structured by including key details like prerequisites or outcomes.

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 involves mutation (linking), has no annotations, and no output schema, the description is incomplete. It doesn't cover behavioral aspects, return values, error conditions, or usage context. For a 3-parameter mutation tool, more information is needed to guide an AI agent effectively.

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%, with clear descriptions for all three parameters (id, session_id, display_title). The description adds minimal value beyond the schema by mentioning 'display title' but doesn't elaborate on parameter meanings, constraints, or interactions. Baseline is 3 since 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 action ('Link'), the resources involved ('Zen (todo) item' and 'Happy session'), and the purpose ('with a display title'). It distinguishes from siblings like happy_zen_create_todo or happy_zen_update_todo by focusing on linking rather than creating or modifying. However, it doesn't explicitly differentiate from all siblings (e.g., happy_zen_set_todo_done might also involve todo items).

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., existing todo and session), exclusions, or compare it to siblings like happy_zen_update_todo (which might also handle linking). Usage is implied by the action but lacks explicit context or alternatives.

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