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

Annotations declare non-read-only, non-idempotent, and non-destructive. The description adds important behavioral details: renewal cannot move the absolute 24-hour limit, no authentication is required, and the owner token must stay secret. These go beyond the annotations and help the agent understand side effects and security constraints.

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?

The description is three concise sentences, front-loaded with the action and key constraints. No unnecessary words or repetition.

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 presence of an output schema and detailed annotations, the description covers all necessary usage aspects: when to use, the 24-hour limit, authentication, and owner token security. No critical information for calling the tool correctly is missing.

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 75% (key, namespace, owner_token have descriptions; ttl_seconds lacks a description). The description itself doesn't add parameter-specific details beyond what the schema already provides, so it doesn't significantly enhance understanding. Baseline of 3 is appropriate given the high schema coverage.

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 states a specific action ('Extend a lease'), the resource ('a lease that this caller still owns'), and a key constraint ('cannot move the absolute 24 hour limit'). It clearly distinguishes from siblings like acquire_lease, complete_lease, and release_lease by focusing on extension of an existing lease.

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?

It provides a clear usage condition: 'Use it before the current TTL ends when work is still running.' It also notes that renewal cannot extend beyond the absolute limit. However, it doesn't explicitly mention alternatives like complete_lease or release_lease, though the context implies them.

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