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

Annotations already declare idempotentHint=true, destructiveHint=false and readOnlyHint=false, so safety is covered. The description adds real value beyond that by stating the lease prerequisite and clarifying that completion is workflow state rather than a verified scientific conclusion, which is a behavioral boundary not encoded in structured fields.

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 sentences, zero waste. The core action is front-loaded and the semantic caveat follows, so an agent reads the operative verb first and the nuance second.

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?

For a 4-required-param mutation tool with annotations and no output schema, the description supplies purpose, prerequisite, and semantic scope. It omits failure/stale-lease behavior, though the schema's fencing note covers that partially, leaving only a minor gap.

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 50% (lease_version and idempotency_key are documented in-schema). The description lightly touches 'summary' and implicitly ties the operation to the lease, but adds no syntax or format detail for task_id or summary beyond what the schema shows. Baseline 3 is appropriate given partial 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?

States a specific verb and resource ('Mark a task complete') plus the scope ('with a summary under your active lease'), and the second sentence clarifies what completion semantically is not. An agent can distinguish this terminal state transition from siblings like create_checkpoint or record_attempt.

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 phrase 'under your active lease' implies the prerequisite that a lease must be held first, which routes the agent contextually. However, there is no explicit when-to-use/when-not guidance nor any named alternative (e.g., record_failure or record_attempt for non-completion outcomes).

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