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

readOnlyHint=true already declares the safety profile, so the description is not obligated to restate it. It does add useful beyond-annotation context by disclosing the composition of the returned payload (description, registration types, registration fields, sessions, counts, totals paid/due), which is the main behavioral unknown for a detail endpoint.

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?

A single front-loaded sentence leads with the verb and enumerates the payload, followed by a compact endpoint reference. No sentence is wasted and nothing is buried.

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 present, the description compensates by listing the returned sub-resources, which is the most important missing structure for a detail fetch. Minor gaps remain around behavior when the event_id does not resolve, but for a simple read-only lookup this is close to 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?

There is only one parameter, event_id, and schema description coverage is 100%, so the schema already carries the full burden. The description adds no format, range, or sourcing guidance for the id beyond what the schema states, so 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 uses a specific verb and resource ('Fetch one event with its details') and enumerates exactly what that detail includes, so the agent knows it is a single-record retrieval rather than a list. It does not explicitly name the contrasting sibling list_events, leaving that differentiation to inference from the name.

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?

Usage is implied rather than stated: 'one event' hints that this is the lookup-by-id counterpart to list_events, but there is no explicit 'use this when you already have an event id' guidance or any exclusion. For a simple single-parameter read tool this is the minimum viable level.

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