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

No annotations are provided, so the description must disclose behaviors itself. It mentions the token is 'fresh' but does not state whether the previous token is invalidated, whether authentication is required, or any rate limits. This leaves important side effects unaddressed for a mutation-like tool.

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 short sentences, with the primary action front-loaded. Every word adds value: 'fresh' and 'book you've already purchased' give necessary context, and 'previous token expired' gives the trigger. No filler.

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 token-refresh tool, it covers the core purpose and usage trigger. However, the lack of annotations and output schema means the description should clarify the return value format and any side effects (e.g., token invalidation), which it does not. Thus it is adequate but not fully complete.

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 baseline is 3. The description adds no extra meaning beyond the schema; it references the entitlement context but does not explain the 'format' parameter beyond what the schema already provides.

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 tool's function with a specific verb ('Get') and resource ('fresh download token for a book you've already purchased'). It distinguishes itself from sibling tools like download_book by focusing on token regeneration rather than the download action itself.

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?

It explicitly says 'Use when a previous token expired,' providing a clear trigger condition. However, it doesn't mention when not to use it or suggest alternatives like download_book if the user simply wants to download a book, so it falls short of full alternative guidance.

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