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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description still adds real value by flagging the candidate's summary as untrusted (a prompt-injection caution) and by bounding the payload ('no contacts or files'). It doesn't describe pagination behavior directly, which keeps it from a 5.

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 dense sentence that front-loads the resource, then the returned fields and the explicit exclusion, with zero filler. Every clause corresponds to something an agent needs.

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 does the work of sketching the return shape (name, role, summary, chat/inbox link) and its limits (no contacts or files), which is exactly what's needed to decide whether to call it. Only the cursor/pagination story is left entirely to the schema.

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%, including the non-obvious 'pass data.next_since from the last call' cursor instruction, so the schema already carries parameter meaning. The description adds nothing on slug or since semantics, which is acceptable at this coverage level but is baseline only.

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?

States the resource precisely ('applications to an event you organize or observe') and enumerates the payload fields, so an agent knows this is a read of applicant records rather than messages or status changes. It does not name the near-siblings (event_application_status, event_application_message, send_event_application), so differentiation is left to inference, keeping it just below a 5.

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?

'an event you organize or observe' implies the access condition and thus when the tool is applicable, but there is no explicit when-to-use/when-not statement and no routing to the sibling tools that handle messaging or status decisions. Usage is implied, not guided.

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