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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with 'Side effects: none (read-only).' It adds valuable behavioral context about the expected 4xx response on first poll and instructs how to present status in everyday words, going beyond what annotations provide.

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 a few sentences long but every sentence earns its place: purpose, parameter guidance, error expectation, and user communication instructions. It is front-loaded with the core purpose and efficiently structured. Slightly long but not verbose.

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 existence of an output schema (not shown), the description need not explain return values. It covers the main usage scenario, error handling, and how to communicate results. It doesn't mention authentication prerequisites, but those are likely implicit for all tools in this set. Overall, it provides sufficient context for correct invocation.

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 schema covers all three parameters with descriptions, so baseline is 3. The description adds meaningful context for wait_seconds (the recommended value after send-fax-uploaded and behavior for later polls), which is beyond the schema. For user_id and fax_id, it adds nothing new, but the existing schema descriptions are sufficient.

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 states the action and resource: 'Get details for a specific fax record.' This is specific and unambiguous, and the tool name reinforces it. While it doesn't explicitly contrast with siblings like get-outbox-fax, the purpose is so clear that an agent can distinguish it without further explanation.

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 gives explicit usage context for the wait_seconds parameter, including when to pass 30 (after send-fax-uploaded) and when to omit it (later polls). It also warns about expected immediate 4xx errors. However, it doesn't mention when to choose this tool over get-outbox-fax or other siblings, though the tool name and context make that reasonably clear.

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