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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond that: results are ordered busiest first and scoped to the last 14 days with per-day counts plus top tools by trace share. It stops short of describing error/auth edge behavior, so not a 5.

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, then enumerates the returned fields (which compensates for the absent output schema), then routes to the sibling. Every clause carries information; there is no filler.

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 — name, send method, 14-day per-day trace counts, and top tools with share. For a single-param read-only list tool with annotations covering safety, nothing an agent needs to call 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 coverage is 100% and the single workspace parameter is fully documented in the schema, including the token/default-workspace rule. The description adds no parameter guidance, so the baseline 3 is correct — the schema does the heavy lifting.

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 (list Caliper sources) and immediately defines what a source is — apps sending agent traces via own code, OpenTelemetry, or a Workbench flow. It explicitly distinguishes itself from the sibling caliper_sources_over_time, so an agent can tell them apart without opening schemas.

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?

Provides explicit when-to-use ("Start here when the user asks how their agent behaves on real traffic") and names the follow-on alternative with its condition ("then caliper_sources_over_time for one source"). Nothing is left to inference.

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