stop_trace

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

Goes well beyond the annotations: it explains the idempotent no-op path (was_tracing:false plus a note instead of an error), the engine Stop() refusal case where stopped is false and size_bytes is absent, the duration_s=0 edge for traces not started by start_trace, and the post-stop guidance to open the .utrace in Unreal Insights. This is exactly the kind of failure-mode 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?

Front-loads the purpose in the first clause, then idempotency, then the return contract — a sensible ordering. The return block is dense and slightly list-like, but every clause carries distinct information (absent fields, zero duration, note semantics) so nothing is wasted.

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?

With no output schema present, the description carries the full return-shape burden and does so thoroughly: it enumerates each field, specifies which fields are omitted in each edge case, and explains the note text. An agent has everything needed to interpret and report the result correctly.

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 parameter semantics is baseline 4 and there is nothing further for the description to disambiguate. The description instead spends its budget on the return shape, which is the right use of space here.

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-plus-resource: 'Stop the active Unreal Insights trace', and names what it returns (destination, duration, file size). An agent can immediately distinguish this from start_trace, get_trace_status and list_traces in the sibling set.

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?

Usage is implied rather than stated: the tool stops whatever trace is currently running, and the description clarifies the no-trace case is safe. However it never names start_trace or get_trace_status as the counterpart tools, nor describes a workflow (start → status → stop) that would route an agent among siblings.

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