usage_events

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

readOnlyHint=true is already declared, and the description still adds significant behavioral context: the exact return envelope, the meaning of truncated, and the explicit warning not to conclude 'no risky prompts were observed' from a truncated result. That goes well beyond the annotation.

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-loaded purpose line followed by a compact Args block and return-contract paragraph; nothing is wasted and the crucial truncation caveat is prominent. The Args list partially echoes schema names, but each entry adds a semantic gloss, so the cost is low.

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 and zero schema-description coverage, the description compensates by documenting the return envelope and the truncation interpretation rule. Nothing an agent needs to invoke or correctly read this call 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 description coverage is 0%, so the description carries the full burden and meets it: all five parameters (model, risk_level, allowed, since, limit) are explained, including the non-obvious allowed=True/False semantics and the enumerated risk bands (none/low/medium/high/critical) absent from the schema. Only the default limit value is left unstated.

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?

Specific verb+resource: 'Query the observed-usage log', with a clarifying parenthetical ('route-through prompts + their findings') that distinguishes it from the raw-scan/policy siblings like scan_prompt and anomaly_report. An agent can identify what this returns without opening the schema.

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?

No explicit when-to-use/when-not versus alternatives among the 20 siblings (e.g., anomaly_report vs raw event listing). It does give filter semantics and a strong interpretation caveat about truncated results, but routing guidance is only implied.

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