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

Annotations declare readOnlyHint=true and openWorldHint=false, so the description doesn't need to restate safety. It adds valuable behavioral context: the estimate is 'certain unless the insurer refiles', the range is built from the plan's own rate changes since 2021, and the key_required error behavior is disclosed. This goes beyond the annotations and helps the agent anticipate failure modes.

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 two sentences with no wasted words. It front-loads the core computation, then the certainty condition, then the range methodology, then the key requirement. Every sentence earns its place.

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 output schema exists and annotations cover safety, the description is nearly complete. It explains the key requirement and the range construction. It could mention what the low/mid/high range represents more explicitly, but the output schema likely covers that. The description is sufficient for an agent to call the tool correctly.

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 the schema already documents all four parameters. The description adds context about 'age plus one' and 'current schedule', which clarifies the age parameter's role, but doesn't add much beyond the schema. Baseline 3 is appropriate because the schema carries the heavy lifting.

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 verb ('estimate') and resource ('renewal premium at age plus one on the current schedule'), and clearly distinguishes it from siblings like price_plans and premium_history by explaining what it computes and its certainty condition. It also names the sibling insurer_increases implicitly by referencing the plan's own rate changes since 2021, which helps an agent differentiate.

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 explains when to use this tool: to estimate renewal cost at age plus one, and notes the key requirement on the public server. It doesn't explicitly say when not to use it or name alternatives, but the context signals and sibling list imply it's for renewal estimation rather than current pricing or historical premium data. The key requirement is a clear usage condition.

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