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

Annotations cover the safety profile (readOnly, idempotent, openWorld, non-destructive), and the description goes well beyond them: it discloses the socket lifecycle budget (5 seconds / 50 messages / 256 KiB then close) and warns that an empty capture is not proof of no changes or no coverage. That is exactly the operational context annotations cannot convey.

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?

Four dense sentences ordered purpose → prerequisites → runtime budget → caveat, with no filler. Slightly information-dense but every sentence 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?

For a read-only streaming capture tool with an existing output schema, the description supplies prerequisites, lifetime limits and interpretation caveats; return-value explanation is correctly delegated to the output schema. Nothing an agent needs to invoke it correctly is missing.

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% with 3 params and a nested filter object holding 5 sub-keys. The description names the event/sport/market/affiliate filter dimensions and echoes the frame/duration ceilings, but leaves main_line and the exact syntax of each filter array unaddressed, so it only partially compensates for the coverage gap.

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+resource+protocol: 'Read actual V2 market-price WebSocket frames', scoped by explicit filters. This clearly separates it from sibling capture_hedge_stream, capture_live_stream and capture_v1_stream, which cover other streams.

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 a clear eligibility gate ('Requires eligible WebSocket access with all periods, live/player-prop access and no delay') and a when-not condition ('restricted custom plans must use REST'). It stops short of naming the specific sibling capture_* tool or REST endpoint an ineligible agent should switch to.

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