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

Annotations only declare readOnlyHint=true, so the description carries the rest and delivers real value: it warns that responses are cached by Breeze and may lag up to 15 minutes, and exposes the underlying `GET /api/events` endpoint. What it does not cover (pagination behavior, whether the cache can be bypassed) keeps it short of 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?

Three tightly packed sentences: scope first, then the critical id-semantics warning, then the caching caveat and endpoint. No filler, and the most decision-relevant fact (which id to pass downstream) is front-loaded after the scope.

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 steps in and explains the two return fields that matter most (`id` = instance id, `event_id` = series) and which sibling tools consume them, plus the default date window and staleness. An agent has everything needed to call and interpret this tool correctly.

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 baseline is 3, but the description adds meaning the schema lacks: the date-range default of the current month and the framing of `category_id` as 'one calendar'. It stops short of explaining `details` or `eligible` further than the schema already does.

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 a specific verb and resource ('List event instances in a date range') with scope (default current month) and an optional calendar filter. It goes further by distinguishing itself from `breeze_get_event` via the instance-id vs series-id distinction, so an agent can tell the two apart without opening schemas.

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 context is implied rather than stated: naming `get_event`, attendance and volunteer tools as consumers of the instance `id` hints at when this list tool is the right entry point, but there is no explicit 'use this when / use X instead when' guidance or exclusion. Nothing is misleading, but the agent must infer the selection rule.

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