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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, yet the description adds substantial context beyond them: X-API-Key requirement, org-scoped visibility, and the deliberate EVENT_NOT_FOUND behavior that masks unknown vs other-org hashes identically. That security/behavioral detail is exactly what structured fields cannot convey.

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?

Purpose is front-loaded in the opening sentence, followed by clearly labeled usage, auth, and return sections. Despite its length, every sentence supplies actionable information rather than 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?

With no output schema, the description compensates by enumerating the returned fields (event_hash, trust_level, trust_label, anchor status, chain metadata) and documents auth and error behavior. An agent has everything needed to call and interpret this tool.

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 single event_hash parameter is already documented, and the description largely restates the 64-char hex format. However it adds genuine semantic value by explaining the failure behavior for unknown or other-org hashes, which the schema does not state.

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 first sentence states a specific verb (fetch), resource (public proof payload), and selector (one ledger event by its 64-char hex event_hash). It clearly distinguishes itself from the sibling list_* and log_* tools that operate on the same ledger entities.

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?

Contains explicit 'When to use' and 'When NOT to use' sections. It names the alternatives (list_agent_decisions / list_agent_outcomes for browsing, log_decision / log_outcome for writes) and the exact condition selecting each, leaving nothing to inference.

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