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

Annotations only declare read-only/idempotent/non-destructive; the description adds meaningful behavior beyond that: auth requirements, the full stage lifecycle semantics and null-for-older-runs caveat, what model_calls/model_spend_usd actually measure (proxy-recorded, null = no meter), and the lower-bound meaning of model_spend_incomplete.

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?

Purpose and scope are front-loaded in the first two sentences, and every subsequent sentence adds a distinct behavioral fact rather than filler. It is dense to the point of being run-on for the field semantics, but nothing is wasted.

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 no output schema and 0% schema coverage, the description compensates by explaining key return fields (stage, model_calls, model_spend_usd, model_spend_incomplete, has_more/next_cursor) and the pagination contract. The only notable gap is the limit parameter's meaning and bounds.

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 0%, so the description carries the full burden. It clarifies test_id ('narrows to an owned test') and cursor (verbatim pagination.next_cursor) plus the has_more loop, but says nothing about the limit parameter or its 1-100 range/default, leaving one of three params fully undocumented.

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 (List), resource (Agent Picks runs) and ordering (newest first by created_at then id), and scopes the corpus ('the project's own', never cloned public results or source artifacts). An agent can distinguish this from get_agent_picks_run (singular) and get_agent_picks_history without opening a 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?

Explicitly routes the agent elsewhere ('Operational records only; use the summary for rates'), states required permissions ('Requires Agent Picks and visibility.read'), gives the pagination loop contract ('Pass pagination.next_cursor verbatim as cursor until has_more is false'), and sets a boundary ('Cannot start or change a run').

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