pix_start_analysis

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

Beyond annotations, it discloses blocking duration, that replay is once-only but continues between calls, free polling, default wait_seconds, and platform-specific behavior including Xbox device_address requirements and possible interruption of the running title. This greatly exceeds annotation coverage.

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 multi-sentence but every sentence earns its place: purpose, performance, blocking/polling behavior, and platform notes. It is front-loaded with the core purpose and key constraints.

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 complex replay tool with no schema descriptions, the description covers nearly all operational context: blocking, waiting, platform differences, and downstream timing queries. It would be fully complete if timeout_seconds semantics were explained and the lifecycle relationship to open/close captures was made explicit.

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 must explain parameters. It gives rich semantics for wait_seconds and device_address, but never explains timeout_seconds and only implicitly references capture_id. This partial compensation earns a middle score.

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 opening sentence states a specific action and resource: replay a capture on a GPU so PIX timing data exists. It also distinguishes itself from the dependent sibling pix_get_event_timing by noting that once ready, timing answers are available at no further cost.

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 clearly implies when to call it: before pix_get_event_timing, and explains polling behavior with wait_seconds=0. It does not explicitly list alternative tools or when not to use it, but the context is clear enough for an agent to route correctly.

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