mfp_log_fast

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

Annotations already declare it's not read-only, not destructive, not idempotent. The description adds useful context: auto-generated uppercase UUIDv4 matching iOS behavior, and the relationship between created id and subsequent update/delete operations. It doesn't contradict annotations.

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 compact, front-loaded with the main purpose, and uses clean Args/Returns sections. Every sentence adds value without 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?

The description covers the essential workflow, return value structure, and id handling. Given the rich nested input schema and annotations, it's sufficiently complete for a create tool. It doesn't address error scenarios, but not necessary for this complexity.

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 top-level schema only has 'params' with no description (0% coverage). The description compensates by listing the nested fields (fast_started, fast_ended, id?, response_format). The nested schema provides detailed semantics for each field, so the description doesn't need to repeat them.

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 uses a specific verb+resource: 'Log a completed intermittent fasting window in MyFitnessPal.' and further clarifies it 'Creates a new entry'. It clearly distinguishes from siblings like mfp_update_fast and mfp_delete_fast by focusing on creation.

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 explicitly explains that the returned id is accepted by mfp_update_fast and mfp_delete_fast, telling the agent when to use those alternatives for modification. It also implies 'use this to create new entries' clearly.

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