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

Annotations already declare this as a safe read (readOnlyHint=true, destructiveHint=false, openWorldHint=false). The description adds genuine behavioral context beyond that: results are restricted to active reminders, sorted soonest-first, and timestamped on the user's local wall clock — the timezone detail in particular is non-obvious and not in the structured fields.

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 what is listed and the ordering, followed by the two details an agent actually needs (timezone basis, id usability). No filler or repetition of the title.

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 an output schema present, return-value shape need not be described, and the three behavioral facts the schema cannot convey — active-only filtering, sort order, and local-clock times — are all covered. Nothing needed to call this correctly is missing.

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 nothing for the description to disambiguate; the baseline for a 0-param tool is 4. The note about what the returned id is used for is a useful touch but does not concern input parameters.

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 active reminders'), plus scope ('active') and ordering ('soonest first'), so the agent knows exactly what comes back. It also links to the sibling cancel_reminder by noting the returned id is what that tool takes, which disambiguates it from cancel_all_reminders and create_reminders.

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?

Usage is implied through the 'active reminders' scope and the pointer to cancel_reminder's id, which sketches a list-then-cancel workflow. However, there is no explicit when-to-use or when-not statement against the many sibling tools, so the guidance remains inferential rather than stated.

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