mfp_add_food_to_diary

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

Annotations carry the mutation profile (readOnlyHint=false, destructiveHint=false, idempotentHint=false), and the description is consistent: adding an entry is a write but not destructive. The description adds a return-value contract (confirmation string) and pins meal to four exact values, but does not disclose edge-case behavior such as duplicate entries or invalid mfp_id handling. With annotations doing the heavy lifting, a 3 is appropriate.

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 front-loaded with a one-sentence purpose, followed by a compact Args section and a Returns line. It is appropriately sized for a four-parameter tool with no fluff, though the Args section partially duplicates the nested schema descriptions.

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 simple diary-add tool, the description covers purpose, the search-first prerequisite, every parameter, and the return format. The main gaps are the lack of explicit routing for update/delete scenarios to sibling tools and no disclosure of failure modes, but these are minor given the annotations and the presence of the output schema.

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?

Despite top-level schema coverage being reported at 0%, the description fully documents all four parameters: mfp_id's provenance from mfp_search_food, the exact valid meal values, date format with default, and quantity as a count of default servings. The meal enumeration and the default-serving clarification add genuine meaning beyond the schema's 'e.g.' phrasing.

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 opening sentence states a specific verb and resource: 'Add a food item to your MyFitnessPal food diary for a specific date and meal.' This unambiguously separates it from siblings like mfp_update_food_entry, mfp_delete_food_entry, and mfp_create_food, since the operation (adding an existing food to a diary for a date/meal) is precisely scoped.

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 establishes the prerequisite workflow: 'You can search for foods using mfp_search_food to find the food ID (mfp_id) needed for this tool.' This tells an agent how the tool fits into a sequence. However, it doesn't explicitly state when not to use it or name alternatives such as mfp_update_food_entry for editing an existing diary entry, leaving some sibling routing to inference.

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