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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial behavior beyond them: the specific conditions flagged (key-changed = CRITICAL, human-only = revoked, balance below ~1 HBAR) and the exact suspicious patterns scanned for. The closing 'Never signs, never spends' reinforces the safety profile with concrete detail.

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?

One dense sentence with the key qualifier ('Read-only health check') front-loaded and no filler. It is on the long side with stacked parentheticals, but each clause carries distinct information.

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 no output schema, the description usefully enumerates what is reported and the flag severities, which is the right burden to carry. It stops short of describing the response shape or how transaction history is windowed, a minor gap for a diagnostic tool.

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 single vault_account_id param is already documented as '0.0.x'. The description adds only the Hedera mainnet context, not parameter syntax or constraints, so the baseline 3 applies.

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 ('Read-only health check for an Agent Vault') plus the concrete things verified: key match, balance, transaction scan. It is clearly distinguishable from siblings like prepare_agent_vault, which set a vault up rather than diagnose one.

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 'health check' — an agent can infer you run it to audit an existing vault — but the description names no alternatives (e.g. prepare_agent_vault for setup) and gives no when-not-to-use condition. Adequate but leaves routing to inference.

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