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

The annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile is covered. The description adds a genuinely non-obvious behavioral constraint — that the fulfillment key is never returned, only on approval — which prevents an agent from mistakenly expecting it. It does not add auth or rate-limit context, so not a 5.

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, front-loaded with the core action and followed immediately by the one caveat that matters. No filler, repetition, or restated title.

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 present, return values need not be enumerated, and the annotations carry the safety profile. The one thing an agent most needs to know that structured fields don't convey — the fulfillment key is withheld — is stated explicitly. Minor gap: no indication of error behavior for an unknown escrow_id.

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 100% and the schema itself supplies the meaning and an example format ('AT-7X9K-2MQ4'), so the baseline is 3. The description adds nothing about escrow_id beyond the schema, but with full coverage the schema does the heavy lifting.

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 clear verb+resource: 'Retrieve metadata about an existing escrow vault.' An agent can distinguish it from create_escrow_vault and evaluate_escrow_work by the read-only lookup framing. It does not, however, explicitly name a sibling or contrast its role against them, so it stops short of a 5.

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 only implied: you call this to inspect an existing vault, keyed by its receipt code. There is no statement of when to prefer this over siblings like view_job, audit_task, or evaluate_escrow_work, and no prerequisites or exclusions are given.

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