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

Annotations already convey readOnly, idempotent, and non-destructive intent. The description adds meaningful behavioral context beyond annotations: the ordering ('newest exit first'), the exhaustive inclusion ('Winners and loserrs both; nothing is excluded'), and the advisory disclaimer ('Signal data, not investment advice').

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?

Three short sentences, each earning its place: core resource and ordering are front-loaded, filtering is stated concisely, and the disclaimer is tucked at the end. No filler or redundant restating of the name.

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 output schema exists and annotations cover safety/idempotency, the description supplies the missing behavioral context: raw replay nature, ordering, filterability, and inclusion of all outcomes. An agent has enough to call the tool correctly without missing key semantics.

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?

Input schema coverage is 100%, with each parameter already described. The description only loosely maps to symbol and exit-date filtering, adding little beyond the schema. Baseline 3 is appropriate because schema does the heavy lifting.

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 identifies a specific resource ('closed-signal historical replay') and concrete behaviors: newest exit first, filterable by symbol and exit date, and inclusive of winners/losers. It is unambiguous but does not explicitly contrast a sibling tool such as list_signals, so it falls short of full sibling differentiation.

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?

No explicit when-to-use guidance or mention of alternatives is provided. The phrase 'historical replay' implies a retrospective purpose, but the description never says when to choose this tool over list_signals, get_signal, or other sibling tools.

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