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

With no annotations provided, the description carries the behavioral burden and does well: it discloses the lease is short-lived, Ed25519-signed, verified offline, fail-closed, and limited to 1 active lease on the free tier. It does not describe the return value or failure/error behavior, but the core behavioral profile is clearly conveyed.

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?

Three tight sentences deliver the core behavior, the verification model, the operational boundary, and the free-tier limit. Every sentence earns its place, and the most important information is front-loaded.

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?

Given the 5-parameter schema and 100% parameter coverage, the description provides a strong overall picture: what the lease is, how it is verified, what actions it guards, and a hard free-tier constraint. The main gap is that no output schema exists and the description does not explicitly state what the function returns or what happens when the free-tier limit is exceeded.

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 description coverage is 100%, and each parameter already has a meaningful description with constraints. The tool description adds context about lease semantics but does not add parameter-level meaning beyond the schema, so the baseline score of 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?

The description names a specific verb ('Grant'), a specific resource ('short-lived, Ed25519-signed LEASE'), and the exact purpose: authorizing an agent to perform an action until expiry. It also distinguishes this tool from siblings like vigil_renew_lease and vigil_revoke_lease by focusing on the initial granting act and calling it 'the guard on a money/data-moving action.'

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?

The description gives clear context: this is the guard for authorizing money/data-moving actions, with offline fail-closed verification by a customer-run gateway. It implies when to use it but does not explicitly contrast it with sibling tools such as renew, revoke, or verify, so no exclusion or alternative guidance is stated.

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