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

Beyond the readOnlyHint annotation, the description details the event structure (severity, source register, deleted flag), the limit of 50 events, and the importance of the deletion flag. This adds significant behavioral context, such as the archival nature of some records.

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, starting with the main purpose, then detailing event types and attributes, providing usage instructions, and ending with a concrete example. Every sentence adds value with no redundancy.

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?

The description explains the return structure, event limit, and key attributes, compensating for the lack of an output schema. However, it does not address error handling or pagination for older events, which would improve completeness.

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 only parameter 'slug' is fully described in the schema, and the description supplements it with an example value and its origin from search_builders. Schema coverage is 100%, and the description adds contextual meaning.

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 it retrieves a dated event timeline for a builder by slug, listing specific event types (licence status changes, deregistration, etc.). This distinguishes it from siblings like search_builders and get_builder_risk, which have different purposes.

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 explains what the tool does but does not explicitly state when to use it versus alternatives like get_builder_risk. It provides an example and indicates when to cite the deletion flag, but lacks general usage guidance.

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