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 reads messages, implying a read-only operation, but doesn't disclose behavioral traits such as permissions needed, rate limits, error handling, or what 'recent' entails (e.g., time-based or count-based). This leaves gaps for a tool with no annotation coverage.

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 two concise sentences that are front-loaded with the core purpose. Every sentence earns its place by stating what the tool does and its use case, with zero waste or redundancy.

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 no annotations, no output schema, and 100% schema coverage, the description is minimally adequate. It covers the basic purpose but lacks details on return values, error conditions, or behavioral context. For a read tool with no structured safety hints, it should do more to inform the agent about what to expect.

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 parameter descriptions in the schema. The description adds no additional meaning beyond the schema, such as format details for session_id or constraints on limit. Baseline is 3 since the schema does the heavy lifting, but the description doesn't compensate with extra context.

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 verb 'Read' and resource 'recent messages from a Happy AI session', making the purpose unambiguous. It distinguishes from siblings like 'happy_send_message' (write) and 'happy_list_sessions' (list metadata), though not explicitly named. However, it could be more specific about what 'recent' means versus 'happy_list_recent_paths'.

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 implies usage for viewing conversation history, which suggests context like after sending a message or starting a session. However, it lacks explicit guidance on when to use this versus alternatives like 'happy_list_sessions' for session metadata or 'happy_send_message' for interaction. No exclusions or prerequisites are mentioned.

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