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

With destructiveHint=true and idempotentHint=false already declared, the description earns credit for explaining the actual destruction mechanism: sending null clears optional fields, an empty string clears text but not numbers or closed lists, and required fields can be changed but never cleared. The tri-state capability guidance (1 / 0 / null, and prefer omission over 0) is genuine behavioral context an agent could not infer from annotations.

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?

Purpose is front-loaded in one clause, then every following sentence states a distinct rule with no restatement of the name or title. The density is warranted for a 16-field nested patch tool.

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 needn't be described, and annotations plus description together cover the mutation/clearing profile. What remains unaddressed is failure behavior on invalid or foreign scale_id values and any permission or ownership constraints beyond the schema's brief note.

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 67%, and the description compensates strongly: it explains patch semantics for the fields object, null-versus-empty-string clearing rules per type, and gives meaning to auto_tare, auto_timer and flow_rate_display, which the schema types only as integer|null with no description. This is meaning well beyond the structured schema.

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 states a specific verb and resource ("Correct a registered scale") and enumerates the editable aspects: type, resolution, capacity, capabilities, build, notes. The word "registered" and the corrective framing distinguish it from register_scale and list_scales without ambiguity.

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?

It gives concrete operating conditions: only keys sent in fields change, fields may be omitted when only reason is sent, and nullable versus required fields behave differently. It doesn't name a sibling alternative (e.g., register_scale for new records) or state prerequisites, so it stops short of full when/when-not guidance.

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