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

Annotations already signal readOnlyHint=true and destructiveHint=false, and the description adds valuable behavioral context: it is 'Public and PII-free,' does not redeem the token, and returns specific fields (name, slug, active/expired/uses remaining). This goes beyond the annotations and gives the agent a clear contract of what will happen.

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 brief paragraphs, with the core action front-loaded in the first sentence. The second paragraph adds return-value details and use cases without any fluff. Every sentence earns its place and the structure is easy to scan.

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, read-only preview tool with no output schema, the description is complete: it states the action, the inputs from the URL, the return fields, the non-destructive nature, and when to use it. No critical information is missing for an agent to decide whether and how to call it.

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 100% and the schema already explains the token parameter with an example URL. The description adds no additional parameter-level detail, so the baseline score of 3 applies. It correctly orients the user to the token concept, but the schema carries the full explanatory burden.

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: 'Look up what a shareable invite link opens, without redeeming it.' It clearly differentiates from a join action and states what is returned (event name, slug, validity), so an agent can immediately understand the tool's function and distinguish it from any join/redemption 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?

The description explicitly says 'Use this before `invite_join`' and gives two concrete use cases: showing the user what they are about to join, and explaining why a link stopped working. However, `invite_join` is not listed among the sibling tools, so the named alternative is not actually available for selection in the provided set, slightly weakening the routing guidance.

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