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 safe-read profile is covered. The description adds genuinely useful context beyond that: it returns no answer, performs no reservation, scheduling or grading, and the queue order is server-time. Return shape ('or card:null') is also disclosed.

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 dense sentences, front-loaded with the return contract before the queue-ordering and filtering rules. Every sentence carries information, though the mutual-exclusivity clause is repeated from the schema, slightly reducing economy.

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 read-only queue-peek tool with a full output schema and fully documented parameters, the description covers return shape, side-effect exclusions, ordering semantics and filter constraints. Nothing an agent needs in order to call it 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?

Schema description coverage is 100%, so all three parameters are documented in the schema, including the mutual exclusivity of tags and deckId. The description restates the mutual exclusivity and filtering intent but adds no syntax or format detail beyond the schema, so the baseline 3 applies.

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 ('Returns one eligible cardId/frontText or card:null') and explicitly scopes it to conversational review without the answer, reservation, scheduling or grading. This cleanly separates it from siblings like reveal_answer and submit_review without opening either schema.

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 clear operative context: server-time queue ordering (due within an hour, other due, then new) and that tags/deckId optionally narrow the queue and are mutually exclusive. It stops short of naming when to prefer it over siblings such as reveal_answer or sql_query, so it is clear but not fully routed.

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