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

Annotations already declare readOnlyHint=true, idempotentHint=true and destructiveHint=false, so the safety profile needs no restating. The description adds genuinely useful non-annotated behavior: finished files are deleted 24 hours after the book is ready, which tells the agent download links are perishable. It does not disclose ordering, result limits, or what 'recent' means, and with no output schema those gaps are left open.

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?

Three short sentences, front-loaded with the action and result, then the trigger condition, then the important expiry caveat. Every sentence carries distinct information with no repetition of the title or annotations.

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?

With no output schema, the description must convey return content, and it does: state per book and download links for completed ones. The 24-hour deletion notice covers the most consequential lifecycle fact. Minor incompleteness remains on how many entries 'recent' returns and whether listing is paginated or bounded.

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 takes zero parameters, so there is no parameter semantics for the description to carry; baseline of 4 applies. Absent any parameters, the agent needs nothing further to construct the call.

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?

States a specific verb and resource ('List the user's recent books on FixMyScan') and enumerates what comes back: state plus download links for finished ones. It also bridges the naming mismatch between the tool name (list_my_scans) and the title/domain term ('books'), which prevents confusion. It stops short of explicitly contrasting itself with get_scan_status, so sibling differentiation is implied rather than stated.

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?

Gives a concrete trigger ('when the user asks about their books') and a second, workflow-oriented one ('or you need a scan_id'), which tells the agent this is the entry point for obtaining the identifier other tools consume. No explicit when-not or named alternative is given, which keeps it out of 5 territory.

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