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

With no annotations, the description carries the full burden; it does disclose that the result is a graded verdict tied to the SmPC in-use limit and that no dosing advice is produced. It omits behavior an agent would want: what happens when situation='left-out' but hours_out/temp_band are missing, whether verdicts are conservative/safety-biased, and any non-medical-advice caveat.

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?

Two tight clauses with the core purpose front-loaded and the conditional inputs immediately after. The parenthetical restatement of the situation values is slight duplication of the enum, but it doubles as usage guidance, so it mostly 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 small, annotation-free tool with no output schema, the description covers purpose, inputs, conditional logic, and a rough return shape. It leaves the 'graded verdict' scale undefined and does not state the failure mode for inconsistent inputs, which is the main remaining 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?

Schema coverage is 50%, so the description compensates meaningfully: it glosses the 'situation' enum values (unopened, in use in the fridge, left out) and makes explicit that hours-out and warmth apply only in the left-out case, which the schema does not state as a conditional rule.

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?

Specific verb ('Say whether...is still good') and specific resource (GLP-1 pen or reconstituted peptide vial), with an explicit scope boundary ('No dosing') that separates it from dosing/medicine-comparison siblings and from device-fault tools like pen_troubleshoot.

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 enumerates the exact situations that select this tool (unopened, in-use-in-fridge, left-out plus duration/temperature) and states an exclusion ('No dosing'), which routes agents away from dosing tools. It does not name a specific alternative sibling such as pen_troubleshoot or howlong_clearance, so it stops short of a 5.

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