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

Adds real behavioral context beyond the annotations: capacity cannot drop below current sign-ups, slots with sign-ups cannot be removed, and participants are not notified of changes. These are the constraints that cause failures and the consequences users care about. It stops short of stating whether the response echoes the updated sheet (the output schema covers that) or how slot-number references are resolved after removals.

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-loads the when-to-use clause, then lists operations, then the call contract, then the constraints. Roughly three dense sentences with no filler; every clause carries either scope, input shape, or a failure condition.

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 10-parameter mutation tool this covers what annotations alone leave open: required organizer credential, partial-update input semantics, two hard validation limits, and the side effect of not notifying participants. Input shape is fully covered by the schema and return shape by the output schema, so nothing material is 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 description coverage is 100%, so the schema already documents every parameter and the baseline is 3. The description nonetheless adds cross-cutting meaning the schema cannot: only the fields to change are supplied, and removal is restricted to empty slots while capacity respects existing sign-ups. That is genuine added semantics rather than restatement.

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?

Names the specific verb and resource (update a sign-up sheet) and enumerates the concrete operations it covers: adding slots, relabeling, changing capacity, removing empty slots, per-person limits, name visibility, note edits, and open/close. It anchors the tool against create_signup_sheet, so an agent can distinguish mutate-existing from create-new immediately.

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?

Explicitly states the trigger ('use this when the organizer wants to change a sheet made with create_signup_sheet'), which names both the condition and the sibling alternative. It also clarifies the call shape ('takes the organizer link and only the changes'), which sets expectations that callers should not resend the whole sheet.

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