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

Annotations already declare this is a non-read-only, non-idempotent, non-destructive write. The description adds one genuinely useful behavioral fact — that the record is written once — which corroborates idempotentHint=false and tells the agent not to retry or expect overwrite. It says nothing about failure behavior or whether session_id must already exist, so it is additive but thin.

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 sentence, front-loaded with the core meaning and using a parenthetical for units/range — no filler. It is arguably compressed to the point of omitting needed usage context, but as structure it is clean.

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 simple four-parameter telemetry write with no output schema and no annotations about returns, the description covers the metric itself but leaves idx/session_id undefined and never states the call ordering (after quiz_answer) or whether duplicate writes are rejected. Adequate minimum, with clear gaps.

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 0%, so the description carries the burden, and it does explain two of four parameters: after_ms units and bounds (0...3,600,000) and the meaning of auto (auto-advance moved on). session_id and idx get no explanation at all, so the compensation is only partial.

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?

The description states exactly what value is being recorded: dwell time on a question after answering, in ms, with the auto-advance flag meaning. That is a specific resource+measurement, not a tautology of the name. It does not, however, tie itself to the sibling it follows (quiz_answer) or distinguish itself from quiz_save/telemetry, so it stops short of a 5.

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?

There is no explicit when-to-use statement, no ordering hint relative to quiz_answer, and no exclusion of alternatives. The only usage signal is the trailing 'Written once', which the agent must interpret on its own.

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