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

Annotations already declare readOnlyHint=false, destructiveHint=true, and idempotentHint=true, so the safety profile is partly covered. The description adds real value beyond that: partial-update semantics ("Only the fields you give are changed"), the return value ("Returns the person's current settings"), and a prompt-injection warning about the untrusted key. It does not explain why the operation is flagged destructive (e.g., that disabling reminders stops future emails).

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?

It is short and front-loads the core action, then layers scope, field semantics, partial-update behavior, return value, and the untrusted-data note. The ownership sentence slightly repeats the "signed-in person's own" phrasing from the first sentence, but no sentence is pure filler.

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 boolean toggle this covers what an agent needs: scope, partial-update behavior, and the fact that settings are returned (no output schema exists, so this matters). The only gap is the unexplained destructiveHint flag, which an agent might want contextualized before disabling a user's reminders.

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 both parameters (including workspaceId sourcing from list_my_workspaces) are already documented in the schema. The description adds only a slight gloss on reminders ("members and admins"), which is close to what the schema's "Email me before my own bookings" already conveys; baseline 3 applies.

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?

"Turn the signed-in person's own booking-reminder emails on or off in one workspace" gives a concrete verb (turn on/off), a concrete resource (booking-reminder emails), and a scope (own settings, single workspace). No sibling tool overlaps this resource, so there is nothing to disambiguate against, which keeps it just short of 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?

The description states a clear usage boundary: "This changes the signed-in person's own settings, never anyone else's," which tells the agent this is the self-service path rather than an admin/member-management tool like update_workspace or invite_member. It does not name an explicit alternative tool, so it stops short of full when/when-not routing.

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