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

With no annotations provided, the description carries the full behavioral burden. The example discloses that rebuild entails a restart, which is useful, but the description never states consequences such as downtime, whether data persists across the rebuild, or any prerequisite instance state. For a disruptive mutating operation this is a noticeable gap.

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?

A single sentence delivers both the action and the canonical use case with no wasted words. The parenthetical example earns its place by clarifying when a rebuild, rather than a simpler lifecycle operation, is warranted.

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 one-parameter tool with full schema coverage, the description covers purpose and a typical trigger scenario. However, with no annotations and no output schema, it leaves the agent to infer post-invocation behavior such as downtime, data persistence, and whether the instance retains its ID.

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% — the id property is fully documented, including its provenance from create_instance or list_instances. The description adds no parameter-specific detail, but none is needed; this matches the baseline of 3 for full 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 on a specific resource — 'Rebuild an instance's pod' — with a concrete example scenario, 'after a config change that needs a restart.' The rebuild/restart framing implicitly separates it from siblings like pause_instance and resume_instance, but no alternative is named explicitly, so it falls short of 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?

The parenthetical example gives a clear trigger condition: use this tool when an instance's configuration has changed and needs a restart. This is concrete context for when to invoke it, though the description does not state when not to use it or name alternative tools.

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