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

Annotations declare destructiveHint=true and readOnlyHint=false, so the mutation profile is covered. The description adds real behavioral context beyond that: earlier days retain their targets, 'through' is inclusive, null stops targets from that day, and confirmation should only follow success. It does not mention permissions or reversibility, but the delivery semantics are unusually well disclosed.

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?

Front-loaded with the core action, then parameter guidance, then the negative-scope caveat and the confirmation rule. Dense but every sentence carries operational instruction; only the 'say so and use it only in this conversation' clause is slightly compressed.

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 values need not be described. For a three-parameter mutation tool, everything an agent needs to call it correctly — date scoping, required value set, stop semantics, unsupported fields, confirmation timing — is present.

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 the baseline is 3. The description nonetheless adds interpretive meaning the schema lacks: 'from' defaults conceptually to today with earlier days untouched, 'through' is inclusive and optional, and null values have stop semantics. This is above the schema-redundant baseline.

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 ('Change the person's daily calorie and macro targets') and scopes it to the user's request context. It is clearly distinguishable from the read-side sibling get_targets.

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?

Explicit when-to-use guidance: 'when they ask', how to use 'through' vs leaving it out, what to do when values are incomplete ('ask for any not given rather than inventing them'), and the null-to-stop case. It also names what the tool cannot do (diet, allergies, iron target) and routes that to conversation instead.

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