get_frame_count

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safe-read profile is covered and 'without side effects' is somewhat redundant. The description still adds real behavioral context the annotations lack: the two distinct counters, their thread semantics, and the differential-measurement pattern.

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, front-loaded with purpose and the usage pattern, then the sibling routing, then the return shape. Every sentence carries information; nothing is padded.

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 zero-parameter read tool with no output schema, the description supplies everything missing: what the counters are, which thread each belongs to, how to use them for measurement, and the exact return structure. An agent has no unanswered questions before calling it.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline is 4. The trailing Returns block documents the two uint64 output fields, which is output rather than parameter semantics but still usefully concrete.

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 ('Read the engine frame counters') and enumerates the exact counters returned (GFrameCounter on the game thread, GFrameCounterRenderThread). It also distinguishes itself from near-neighbors by naming frame_timing and get_fps_info as the tools for frame times, so an agent can separate this from siblings without opening any 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 an explicit usage pattern ('read it before and after another call to measure how many frames ticked') and names the two alternatives for a related but different need (frame times). Both when-to-use and when-to-use-something-else are covered.

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