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

Annotations already declare readOnlyHint, idempotentHint and destructiveHint=false, so "Changes nothing" is partly redundant reinforcement. The description adds value annotations cannot carry: the pedagogical/sequence constraint (reveal only after an attempt), which prevents an agent from short-circuiting the review loop.

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?

A single compact sentence with the return value first and the usage constraint second; nothing is padded and no clause could be removed without losing information.

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 covering return values, full schema coverage on both params, and annotations covering the safety profile, the description only needs to supply the workflow gate — which it does. Nothing material is missing for a correct invocation.

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% and both parameters are documented in the schema itself (cardId sourced from next_review_card, workspaceId defaulting to selected). The description adds no format or defaulting detail beyond that, 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?

Names a concrete verb+resource plus the field returned ("Returns a card's backText"), which is more specific than a bare 'get answer'. It also ties into the review flow by referencing the learner's attempt, though it does not explicitly name the sibling tools it complements.

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?

"call it only after they answer" gives an explicit precondition and implies the next_review_card → answer → reveal_answer sequence. It stops short of naming an alternative tool or a when-not-to-call case, but the ordering constraint is clear.

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