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

Beyond the annotations it discloses exactly what state changes (existing reminders are replaced, an empty list wipes them including the automatic one), who is reached (unreplied, Yes and Maybe guests), that reminder text is immutable, that RSVP-off disables it, plus confirmation and auth requirements (Cotlet API key, confirm before each call). That is materially more than readOnlyHint=false/openWorldHint=true already tell the agent.

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?

Front-loaded correctly, but it repeats itself: 'Up to 5, each at least 30 minutes from now' is stated twice, and the confirmation behavior appears in two sentences ('By default you confirm each call...' and 'Reaches other people: confirm with the user before each call'). The 'Evite:' prefix also duplicates the title. Tighter editing would lose nothing.

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 two-parameter write tool with no output schema, the description covers the write semantics, who gets notified, immutability of content, availability gating, and user-confirmation/auth preconditions. Nothing an agent needs to invoke it safely appears to be missing.

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 a constraint the schema lacks: reminders must be no later than 30 minutes before the event starts. It also restates the 5-item and empty-list behavior, which is mild redundancy with the 100%-covered schema.

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+resource ('Replace the event's reminders') and makes the reminder-specific scope unmistakable against siblings like evite_send_invitation and evite_message_guests. An agent knows this is the reminder-scheduling tool, not an invite or messaging tool, without opening the schema.

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?

It supplies strong usage conditions (max 5 reminders, timing window relative to now and the event start) and an explicit exclusion ('Not available when RSVPs are off'). It stops short of naming alternative sibling tools an agent might pick instead, so it is clear context rather than full when/when-not/alternative routing.

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