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

Annotations already declare readOnly=false, idempotent=false, destructive=false, so the safety profile is covered. The description usefully adds that the lease must be active and that a fencing number is required, but it never states that renewal extends the lease lifetime (which the lease_seconds parameter implies) or what a fence mismatch does. Adds some value beyond annotations, not rich.

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, zero waste, with the core operation front-loaded and the constraint following. Nothing could be trimmed without losing 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 an output schema present, return values need no explanation, and annotations carry the safety profile. The one meaningful gap is that renewal semantics (that it resets the lease clock via lease_seconds) are left for the agent to infer from the schema alone.

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%, so all four parameters are already documented in the schema, including fence meaning and lease_seconds defaults. The description only restates token and fence at a high level, adding no format or constraint detail beyond what the schema provides. Baseline 3 is appropriate.

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 (renew) and resource (lease) and names the two credentials required (secret token, fencing number), so the agent knows exactly what operation this is. It does not explicitly contrast with siblings like release_lease or claim_task, so a 4 rather than 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?

"Renew an active lease" plus "Expired or stale leases cannot renew" gives a clear precondition and a when-not condition, which is more than most definitions offer. It still names no alternative tool for acquiring or releasing a lease, so it falls short of explicit routing guidance.

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