trace_start

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

Annotations declare readOnlyHint=false, so the agent already knows this creates state; the description usefully adds that a trace_id is returned and that names can be auto-generated. It does not disclose persistence, lifecycle constraints, or limits on concurrent traces, so it adds moderate 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?

Three short sentences, front-loaded with purpose and the return value, with no filler. The inline example object is slightly redundant given the schema but does not bloat the text.

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 one-parameter state-creating tool with no output schema, the description covers purpose, return value, and the auto-naming option, and annotations cover the safety profile. Missing only lifecycle-adjacent context such as whether traces must be explicitly ended.

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%, so the schema already documents the single name parameter fully; baseline is 3. The description largely restates the schema's 'auto' behavior, and its 'leave name blank' suggestion sits awkwardly against a parameter marked required.

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 and resource ('Begin a new agent workflow trace') and clarifies the return value (a trace_id). The start-of-lifecycle role is clear against siblings like trace_step and trace_end, but no sibling is named explicitly, so differentiation is inferred rather than stated.

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 line 'Returns a trace_id to use with subsequent calls' implies the tool is used first, before trace_step/trace_end, but it never states when not to use it or names an alternative. Guidance is present but must be inferred.

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