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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is established. The description adds useful context about exhaustiveness and content (every error code, meanings, retry guidance), but it does not describe the response format or potential size. No contradiction with 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 entire description is one focused sentence with no filler. The core identity ('machine-readable catalog of every error code') comes first, followed immediately by the value-add details of meanings and retry guidance.

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 zero-parameter read-only tool, the description conveys the essential information: what the catalog contains and why an agent would use it. It does not explicitly state the output shape, but the tool is simple enough that this is 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?

The tool has zero parameters and an empty input schema, so there is nothing to document. Per the rubric, zero parameters receive a baseline of 4; the description does not need to add parameter-level detail.

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 as a machine-readable catalog of every Epsilon API error code and explicitly states the two key contents: meanings and retry guidance. No sibling tool appears to cover error codes, so there is no ambiguity about what this tool does.

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 makes the use case clear: consult this catalog when an agent needs to interpret an API error or determine retry behavior. It does not explicitly name alternatives or exclusions, but no error-focused sibling exists, and the read-only lookup context is unambiguous.

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