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

Annotations already declare destructiveHint and idempotentHint, so the description's job is to add nuance — which it does: 'the reason is recorded with a timestamp' and 'the first reason wins' explain exactly what happens on a repeat call, a detail the idempotentHint alone does not convey. It stops short of stating whether the stop is reversible or what happens to in-flight work.

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 sentences, zero waste, consequence front-loaded before the idempotency caveat. Nothing to trim.

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 two-parameter destructive tool with an output schema, the description covers effect, side effect, and retry behavior. Gaps are minor: no precondition (must the envelope be open?) and no note on permissions or whether an already-killed envelope raises an error.

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 0% for two parameters, so the description must carry meaning — it gives real semantics for 'reason' (recorded with a timestamp, first value wins on retry) but says nothing about 'envelope_id' beyond the verb phrase 'one task envelope'. Partial compensation, not full.

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 — 'Stop one task envelope immediately' — plus the consequence ('no further spend is approved'). Clear enough to distinguish from open_envelope, though the description never names that sibling as the opposite operation, so differentiation is implicit rather than explicit.

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?

Usage is implied by 'no further spend is approved for it' — an agent can infer this is the tool for halting spend on an envelope. But there is no explicit when-to-use, no exclusion (e.g., don't use on already-closed envelopes), and no reference to open_envelope or check_spend as alternatives.

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