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

readOnlyHint=true already covers the safety profile. The description adds the important behavioral detail that contact_id overrides other filters, which goes beyond annotations. But it doesn't disclose pagination behavior or return format.

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 terse sentences that front-load the core purpose, then the filter behavior, then the API reference. Every sentence earns its place.

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?

Adequate for a read-only list tool with full schema coverage and annotations covering safety. It lacks return format/pagination detail, but for a read-only listing tool this is a minor gap.

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 schema documents all 8 parameters thoroughly. The description adds the contact_id precedence rule, which is meaningful, but beyond that the schema does the heavy lifting. Baseline 3 is appropriate.

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+resource (list calendar events) with scope (date range) and filter dimensions (user or calendar). It's clear, though it doesn't differentiate from the create_event sibling which is a different operation anyway, so a 4 is warranted.

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?

Provides a clear conditional rule: if contact_id is given, all events attached to that contact are returned and other filters are ignored. This is important guidance about precedence. However, no explicit when-to-use-this-vs-alternatives guidance relative to siblings.

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