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

The readOnlyHint annotation already establishes that this is a safe read operation. The description adds the API endpoint and the fact that it returns a full history over time, which is useful behavioral context, but it does not mention pagination, response format, or any limits on the returned history.

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, and the core purpose is front-loaded before the API endpoint detail.

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 simple read-only list tool with one documented parameter and readOnlyHint coverage, the description provides enough context to invoke the tool correctly. It only lacks return-value details such as ordering or pagination, but no output schema exists and the core behavior is clear.

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 single customer_id parameter is already documented. The description adds the API query parameter spelling CustomerId=<id>, but does not add meaning beyond what the schema provides, matching the baseline 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 verb and resource: list the full history of product plans assigned to a customer over time. It clearly scopes the operation to historical data, which helps distinguish it from a current-plan tool, though it does not explicitly name the sibling it differs from.

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?

Usage is implied by 'full history ... over time,' suggesting the tool is for retrieving historical assignments. However, it does not explicitly say when to use this versus the sibling get_customer_plan or other plan-related tools, so the agent must infer the selection criteria.

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