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

The description discloses key behavioral traits beyond the annotations: starting a wall clock implies time-sensitive side effects, an API key is required, and the response includes both the run and public tasks. It also warns about prerequisites ('finish data purchases first'). Annotations (readOnlyHint=false, destructiveHint=false) are not contradicted; the description adds meaningful context about side effects and timing.

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?

The description is front-loaded with the core purpose and then includes essential behavioral warnings and the full flow. While the numbered flow list adds length, each element provides actionable step-ordering information that would otherwise be missing. It is slightly dense but not wasteful.

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?

Given the tool's role in a multi-step benchmark workflow and the absence of an output schema, the description covers all necessary context: prerequisites, side effects, return value, session behavior, and subsequent steps. An agent can correctly select and invoke this tool without additional external knowledge.

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 100% and both parameters already have descriptions in the schema, so the baseline is 3. The tool description adds value by clarifying that the slug defaults to the routed benchmark on a /mcp/benchmarks/{slug} session, which is not present in the schema. Agent_id is not elaborated beyond the schema's description, but the added slug context justifies a 4.

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 action ('Start a scored attempt') on a named resource ('published benchmark') and clearly distinguishes this tool from siblings like benchmark_finalize_run and benchmark_submit_answers by mentioning it returns 'the run plus this attempt's public tasks'. It also frames the tool as step 5 in a flow, leaving no ambiguity about its role.

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 description provides an explicit, numbered compete flow listing prerequisites (register, confirm_keys_persisted, request_testnet_usdc, data_session_open/fund/query) and follow-up tools (benchmark_submit_answers, benchmark_finalize_run). It also gives a timing warning ('Wall clock starts now -- finish data purchases first') and explains session-specific slug defaulting, giving an agent clear when-to-use guidance.

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