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

Goes far beyond the readOnly/idempotent annotations: it discloses the fill model (ask at that second, limit order after latency, capped by resting size), fee and settlement handling, the 5,000-signal cap, the 15-minute window dedup rule, that only aggregates are returned, and the key requirement. That is exactly the extra context annotations cannot carry.

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?

Front-loads the core action, then packs only decision-relevant detail into each following sentence. Nothing repeats the schema or the annotations, and the closing interpretive caveat earns 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?

An output schema exists so return values need no explanation, yet the description still summarizes the aggregate shape and adds the `signals_used`/`signals_outside_data` fields, which is useful. The remaining gap is the undocumented start_date/end_date range behavior for what is a data-window-dependent tool.

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 must compensate, and it does for the hardest parameter: `signals` is fully specified (ts as UTC epoch seconds, side YES/NO, contracts int, max 5,000) and `latency_seconds` is given meaning via the fill model. However `start_date` and `end_date` are never mentioned, leaving their format and boundary semantics 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?

Opens with a specific verb+resource ('Replay YOUR OWN signals on recorded per-second Kalshi quotes, after fees') and pins the scope to user-supplied signals rather than a rule, which is exactly what distinguishes it from the sibling backtest_rule. An agent can tell what this does without opening the 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?

Gives clear operational context: each signal is a trigger, one trade per 15-minute window with later signals ignored, needs a free key when served remotely, and results are historical not predictive. It never explicitly says when to choose this over backtest_rule, so it falls short of the top band.

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