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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), so the bar is lower, and the description still adds genuinely useful behavior: the shape of the returned step list and the 2,000-character truncation limit on long values. It omits error behavior for a missing trace, but the truncation disclosure is real added value beyond the annotations.

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?

Content is front-loaded ("One trace: what came in, what went out, and every step in order"), with truncation and intended use following. The middle clause is dense with parentheticals, but each earns its place by telling the agent what fields to expect.

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, the description carries the return-value burden and does so well by enumerating call types and their fields plus the truncation limit; the annotations handle safety and the schema handles input routing. Only the failure mode for an unknown traceId is unaddressed, which is a minor gap.

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 100%, and the schema already documents all three parameters including the workspace/token default rules and where traceId and sourceId come from. The description adds no parameter detail, so the baseline 3 applies.

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 makes clear this retrieves a single trace and enumerates exactly what it contains (model calls, tool calls, lookups, timing, status), which implicitly contrasts with the sibling caliper_traces_list. It never states a plain verb like 'retrieve one trace by id', but the resource and scope are unmistakable.

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?

"Use it to explain why one conversation went the way it did" gives one concrete debugging scenario, and the schema's traceId note points back to caliper_traces_list as the source of ids. However there is no explicit when-not guidance or statement of the list-then-get workflow in the description itself.

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