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 this is a list operation but doesn't disclose important behavioral traits: whether it lists all items or is paginated, if there are any filters or sorting options, what authentication is required, or how the data is returned. For a list operation with zero annotation coverage, this leaves significant behavioral questions unanswered.

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 communicates the core functionality. It's appropriately sized for a simple list operation with no parameters. Every word earns its place - 'List' (verb), 'Zen (todo) items' (resource), and the specific attributes returned. No wasted words or unnecessary elaboration.

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 multiple sibling tools, the description is incomplete. It doesn't explain the return format, whether it's paginated, how results are structured, or how it differs from other list operations. For a tool in a server with 14 sibling tools including multiple list operations, more context about this specific list's scope and behavior would be helpful.

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 tool has 0 parameters with 100% schema description coverage. The description doesn't need to explain parameters since none exist. It appropriately focuses on what the tool does rather than parameter details. The baseline for 0 parameters with high schema coverage is 4, as there's nothing to compensate for.

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 'List' and resource 'Zen (todo) items' with specific attributes (titles, descriptions, completion status). It distinguishes from siblings like create/delete/update/set_done operations but doesn't explicitly differentiate from other list tools on the server. The purpose is specific but could be more distinctive among multiple list operations.

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. There are multiple list tools on the server (list_environment_sets, list_machines, list_recent_paths, list_sessions) and other Zen todo operations (create, delete, update, set_done), but the description offers no context about when this specific list operation is appropriate versus other listing or todo management tools.

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