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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the safety profile is largely covered. The description adds the partial-update instruction ("send only what changes"), but it fails to disclose that the nested kettlebells object requires all three weight classes, so sending a partial kettlebells payload effectively overwrites the rest — the core destructive risk here.

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?

Two short sentences with the mutation target front-loaded and zero filler. The only inefficiency is the dangling pronoun "they," which costs a little clarity without adding bulk.

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 no output schema and only two parameters, the description is nearly sufficient, but it omits the nested-object replacement behavior and any indication of what a successful update returns or whether it applies to the caller's own profile. For a destructive, nested-payload mutation, those gaps matter.

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 100%, with the enum for mix and per-weight semantics for kettlebells fully documented in the schema, so the baseline is 3. The description's paraphrase of "how they build endurance (mix)" and "which kettlebells they have" adds no syntax, format or constraint detail beyond what the schema already states.

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 mutation ("Changes") over two named profile attributes: endurance mix and kettlebells. An agent can tell this is the write counterpart to my_profile, though the description never names that read sibling to sharpen differentiation. The awkward phrasing "how they build endurance" leaves the subject (the user's profile) implicit.

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?

"Send only what changes" gives a useful partial-update cue, which is meaningful since all parameters are optional. However, there is no explicit when-to-use guidance, no mention of when not to call it, and no reference to my_profile as the read alternative or to any precondition for editing a profile.

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