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

With no annotations, the description carries the burden of behavioral disclosure. It does so well by explaining the free-tier vs full-tier difference ('complete record for sample events... classification facts for all others... deeper assessment and evidence withheld'). The read-only nature is implied by 'Retrieve', though not stated as explicitly as with a readOnly 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?

The description is information-dense but every sentence earns its place: the purpose, the content returned, the routing guidance, the ID format, and tier-based behavior. It is front-loaded with the core action and avoids filler.

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 single-parameter lookup tool with no output schema and no annotations, this description covers everything an agent needs to call it correctly: what fields come back, how to format the ID, when to use it, and how the response varies by tier. No critical gap remains.

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 event_id parameter as a zero-padded string with examples. The description repeats this guidance but adds no new meaning about the parameter beyond what the schema provides. The baseline of 3 applies.

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 opens with a specific verb and resource: 'Retrieve one event by ID', and enumerates the record contents (classification, assessment, sources, industry tags, ENTs, bloc analysis, tier rationale). It distinguishes itself from search_events by clarifying this is a direct lookup rather than a discovery tool.

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?

'Use when you already hold an event ID; to find IDs, use `search_events`' is an explicit, actionable usage rule. It tells the agent the exact condition for calling this tool and names the sibling to use instead. No inference is required.

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