check_food_fit

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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so the non-mutating nature is covered structurally. The description adds that the result is a projection (current + addition + remainder), which clarifies behavior beyond the annotations, but it says nothing further about auth, limits, or that no entry is written — a point worth stating explicitly for a tool whose sibling logs food.

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 core behavior is front-loaded in the first two sentences, followed by a compact Args block. It is appropriately sized for a three-parameter tool with only minor redundancy with the output schema.

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?

With an output schema present, the description need not detail return shape, yet it still frames the result usefully. Combined with full parameter documentation, an agent has enough to call it correctly; the only soft gap is the absence of explicit routing guidance versus the logging siblings.

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 0%, so the description carries the full burden and does it well: it documents food_id's provenance (from search_foods), gives grams an explicit unit, and gives date a format plus a default of today — resolving the schema's ambiguous null default. All three parameters are covered with meaning beyond their names.

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 opens with a specific hypothetical question and then enumerates exactly what the tool returns: the day's current calories/macros, the food's contribution, and the remaining budget. That makes it clearly a projection/what-if tool rather than a logging tool like add_food_entry, though it never names a sibling explicitly.

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?

Usage is implied by the "still fit today's targets?" framing — an agent can infer this is a pre-logging check. There is no explicit statement of when to use it versus add_food_entry or analyze_day, and no exclusions or prerequisites given.

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