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 mentions the tool lists 'recently used folder paths' and hints at use for session starting, but doesn't disclose behavioral traits like whether this is a read-only operation, what format the output returns, if there are rate limits, or authentication needs. For a tool with no annotations, this leaves significant gaps.

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 with two concise sentences that are front-loaded with the main purpose. Every sentence adds value, though it could be slightly more structured by separating purpose from usage hint.

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 and no output schema, the description is minimally adequate for a simple listing tool but lacks completeness. It covers the basic purpose and a usage hint, but doesn't address output format, error conditions, or detailed behavioral context, leaving room for improvement in a tool with 2 parameters.

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 fully documents both parameters (machine_id and limit). The description adds no additional meaning beyond what the schema provides, such as explaining what 'recently used' means or how paths are ordered. Baseline 3 is appropriate when 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 ('List recently used folder paths') and resource ('for a machine'), providing a specific verb+resource combination. However, it doesn't explicitly differentiate from sibling tools like 'happy_list_machines' or 'happy_list_sessions' which also list things, missing full sibling distinction.

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 implied usage context ('Useful for starting sessions in familiar locations'), suggesting when this tool might be helpful, but doesn't explicitly state when to use it versus alternatives or any exclusions. No clear guidance on prerequisites or comparisons to other listing tools.

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