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

With no annotations, the description carries the full burden, and it does disclose two non-obvious traits: the test is timed and the human account owner (not the agent) must be the taker, which is a genuine actor/auth constraint. It omits whether starting is idempotent, what happens if a test is already in progress, and any rate or state limits.

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 short sentences, front-loaded with the action and its timing constraint. Nothing is padded, though the parenthetical '(seeker key)' is ambiguous enough that it costs clarity rather than earning 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 state-changing tool with no annotations, no output schema, and an undocumented parameter, the description covers the most important behavioral fact (a human must take the test) but not the surrounding flow: what 'start' produces, how the skill is chosen, or how this connects to submit_test. Adequate but with visible 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?

There is a single required 'skill' parameter at 0% schema description coverage, so the description must compensate and largely does not. '(seeker key)' is cryptic and appears to describe a credential context rather than the 'skill' argument itself; the description never explains what value 'skill' accepts (ID, name, enum from list_skill_tests).

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 a specific verb+resource ('Start a timed skills test') and adds a scope qualifier ('seeker key'), which distinguishes it from submit_test and list_skill_tests by implying initiation rather than submission or listing. It stops short of naming a sibling explicitly, so differentiation is inferable rather than stated.

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 line 'The human account owner must take it' gives a real applicability condition — this is not an agent-executable step but one requiring the human account holder — which is meaningful routing guidance. However, it never says when to call this versus submit_test, or what must precede it (e.g., whether a test must be selected from list_skill_tests first).

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