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

The readOnlyHint annotation already communicates the non-mutating nature. The description adds genuinely useful behavioral context about blocked free tier, tier-specific lookback limits, and the archive's scope, but it does not disclose error behavior on blocked access, pagination details, or response ordering. No contradiction with 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?

The description is two concise sentences with the primary action and scope front-loaded. Every sentence adds relevant information: the first defines what the tool returns, the second defines access constraints. There is no filler or 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?

For a tool with no required parameters, 100% schema coverage, and a readOnly annotation, the description provides sufficient access and scope context to invoke it correctly. Minor gaps remain: the response shape is not described, pagination behavior is not mentioned, and the relationship to list_incidents is left implicit, so it is not maximally complete.

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 schema already documents all five parameters at 100% coverage, so the baseline is 3. The description adds meaning beyond the schema by quantifying what 'Tier-limited' on the after parameter means: Starter gets 1 year, Developer/Business get 5 years, and Pro/Enterprise get unlimited access, plus free tier is blocked.

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 uses a specific verb and resource ('Returns historical emergency incidents from the 4.8M+ record archive (1840-2026)') and clearly identifies this as a read-oriented historical lookup tool. It does not explicitly call out the difference from siblings like list_incidents or list_events, so it misses a point for sibling differentiation.

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?

It gives clear context about when the tool can be used by describing paid-tier access and lookback limits, which is useful for eligibility decisions. However, it does not state when to prefer this over sibling tools such as list_incidents or nearby_incidents, nor does it provide exclusions or alternatives.

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