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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real domain behavior beyond that: 'Only meals in a result exist; never claim others do' is an explicit anti-hallucination guard, and the note that partial days from list_days are missing meals and must be excluded from averages and low-day claims is non-obvious operational context.

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 purpose and filter modes are front-loaded in the first two sentences with no filler. The closing sentence about partial days is valuable but grammatically mangled ('A day list_days marks partial is missing meals'), which costs it a point.

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?

An output schema exists, so return-shape explanation is unnecessary. With 8 optional params, the description covers filter selection and the partial-day caveat adequately; only pagination (offset/nextOffset) is absent from the prose, though the schema documents it.

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 coverage is 100%, so a 3 baseline would be defensible, but the description adds relational meaning the flat schema cannot convey: day / fromDay-toDay / from-to are alternative filter modes, and fromDay/toDay are inclusive local dates suited to a week range. It says less about limit or offset, which the schema already documents.

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?

States a specific verb and resource (read the person's saved meals) plus ordering (newest first), which cleanly separates it from get_meal (single meal), list_days, and list_foods. An agent can tell what this tool returns without opening the schema.

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?

Explicitly enumerates the filtering modes and when each applies: 'day' for a single date, 'fromDay/toDay' for an inclusive local-date range such as a week, 'from/to' for timestamps, and 'state' to see plans or eaten meals. It also gives cross-tool guidance about list_days partial days. It stops short of naming exclusions against siblings like get_meal, so it is not a full 5.

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