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

Adds genuinely non-obvious behavior beyond the annotations: partial update semantics and the fact that `options` deep-merges rather than replaces. It does not explain why destructiveHint=true (that array fields like `series`/`filter` are wholesale replaced), which is the one behavioral detail an agent most needs warned about.

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 dense sentences, front-loaded with the field list followed by the mutation semantics; nothing is wasted and the merge caveat lands where it matters.

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 and annotations present, the description only needs to add behavior — and it does, covering partial updates, options merging, and the create-shape reference. Only the destructive overwrite of array fields is missing for full completeness.

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 only 44% across 9 params, so the description carries real weight: it names every updatable field and points to widget.create's shape for their structure, and clarifies that `options` merges into existing ones. It still leaves the replacement-vs-merge distinction for `series`/`filter` unstated.

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 concrete verb (change) plus the resource (widget) and enumerates the mutable fields, so the scope is unambiguous. Explicitly anchors it to widget.create's shape, which cleanly separates it from create/delete/restore siblings.

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 partial-update rule ('Only what you pass changes') implies how to use it safely, but there is no explicit when-to-use guidance, no preconditions, and no routing to alternatives (e.g. widget.delete/restore). Usage must be inferred.

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