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

Annotations already establish read-only and non-destructive behavior. The description adds useful context beyond annotations by explaining that Canadian answers differ from American figures and that entries explicitly call out the American answer where it differs. This helps the agent set expectations about the response content without contradicting the annotations.

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 purposeful sentences with no filler: it front-loads the topic, adds a valuable Canadian-vs-American nuance, and ends with a direct invocation cue. 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?

For a no-parameter, annotated, read-only tool with an output schema, the description is complete. It covers what the tool returns, the scope, a key nuance (Canadian vs American periods), and when to call it, so an agent has everything needed to select and invoke it 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?

There are no parameters, so the description cannot add parameter-level meaning. The baseline of 4 applies because the scope statement ('Retention periods on a Canadian credit file') appropriately substitutes for parameter guidance.

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 clearly identifies the resource (retention periods on a Canadian credit file), lists the major categories it covers, and explicitly assigns the tool to 'how long will this stay on my credit report' questions. This differentiates it from siblings like when_issuers_report and payoff_timeline.

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 final sentence states exactly when to invoke the tool: 'Call this for any "how long will this stay on my credit report" question.' It does not name alternatives or exclusions, but for a no-parameter reference tool the when-to-use guidance is clear and sufficient.

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