cronometer-mcp

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

With no annotations provided, the description carries full burden. It clearly indicates this is a mutation operation ('Cancel') and specifies important behavioral constraints (only works on active fasts, preserves recurring schedules). However, it doesn't mention authentication requirements, rate limits, or error conditions.

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 perfectly structured with a clear purpose statement, usage guidance, and parameter explanation in just three sentences. Every sentence adds essential information 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?

For a mutation tool with no annotations, the description does an excellent job covering purpose, usage, and parameter semantics. The presence of an output schema reduces the need to describe return values. However, it could benefit from mentioning authentication requirements or error handling for a cancellation operation.

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 description adds crucial semantic context for the single parameter beyond the schema's 0% coverage. It explains that 'fast_id' refers to 'the fast ID of the active fast to cancel' and provides guidance on how to obtain valid IDs via 'get_fasting_history'. This compensates well for the schema's lack of descriptions.

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 ('Cancel an active fast') and distinguishes it from sibling tools by specifying it preserves the recurring schedule. It explicitly differentiates from 'delete_fast' by focusing on active fasts only.

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 explicit guidance on when to use this tool (for active fasts) and directs users to 'get_fasting_history' to find eligible fasts. It also implicitly distinguishes from 'delete_fast' by emphasizing preservation of recurring schedules.

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