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

Annotations already declare a write/destructive, closed-world operation, so the bar is lower — yet the description adds substantial behavior beyond them: partial-update semantics ("Only what you pass changes"), that readings are untouched, conflict-on-rename failure, and a possible needs_confirmation envelope. These are exactly the non-obvious traits an agent needs before invoking a 13-param mutation.

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 editable facets, then the operational constraints (readings untouched, partial update, slug locked, conflict, confirmation). Dense but every sentence carries distinct information; no filler.

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?

For a 13-param mutation with no output schema, the description covers the critical gaps: partial update, non-editable slug, conflict behavior, and the needs_confirmation return signal. It does not explain the approvalId/confirmation round-trip in detail, which is the only remaining loose end.

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 85%, so the schema does most of the work (unit, kind, level, drives, target, cadence are all documented inline). The description still adds value by flagging the partial-update contract, the metricId provenance, and the non-editability of slug, which the schema does not state.

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?

Specific verb+resource ("Corrects a metric's definition") followed by the full list of editable facets, which pins down exactly what this tool mutates versus ledger_metrics_create/archive/record_reading. It also explicitly states what is NOT editable (the slug) and where metricId comes from, so an agent can distinguish it from siblings without opening any 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?

Gives clear operating context: metricId must be sourced from ledger_metrics_list, the slug is out of scope here, and renames collide with live metrics. It stops short of explicit when-to-use-this-vs-create/archive routing, but the scope statements make the intended usage unambiguous.

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