log_span

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

No annotations are provided, so the description carries the full burden. It discloses that the tool records a span and returns a span_id, but does not discuss side effects, idempotency, permissions, or error behavior. This is adequate but not rich.

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?

The description is well-structured with a clear header, usage example, and parameter list. It is appropriately sized for 8 parameters, though slightly verbose with the example. Every sentence adds value.

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?

Given the tool's simplicity (logging a span with 8 parameters, mostly optional), the description covers the core functionality and return value. However, it lacks information about error handling, duplicate detection, or authentication requirements, leaving minor gaps.

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?

Although the input schema lacks descriptions (0% coverage), the tool description includes a detailed Args section explaining each parameter (name, duration_ms, kind, etc.). This adds significant meaning beyond the schema, compensating well for the schema gap.

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 clearly states the tool records a completed span in one call, distinguishing it from sibling tools like start_span and end_span. It uses a specific verb (Record) and resource (completed span), and provides an example of retrospective timing data.

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 description explicitly states when to use the tool ('for logging retrospective timing data') and contrasts it with needing separate start/end calls, implying when not to use it. However, it does not explicitly name alternative tools or provide exclusionary guidance.

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