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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=false, so the bar is lower, but the description adds no behavioral context at all. It does not say that the original slot is released or replaced, whether the old booking is cancelled, whether the caller must reconfirm, or what happens on conflict.

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?

A single clause with no filler, front-loaded with the verb and resource. It is efficient, though it spends its space restating the title rather than adding qualifying detail.

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 mutation with full schema coverage and annotations carrying the safety profile, the essentials are covered by structured fields. Still, with no output schema, the description should say what a successful reschedule yields (a new or updated booking ID, confirmation) and whether the prior booking remains valid.

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%: bookingId carries strong guidance about sourcing the ID from a prior book_appointment call and never guessing it, and startTime is typed as an ISO 8601 date-time. The description adds nothing beyond that, so the 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?

"Reschedule an existing appointment" names a specific verb and resource, and the word "reschedule" naturally distinguishes it from the sibling tools book_appointment and cancel_appointment. However, it does not explicitly name or route to those siblings, so the differentiation is inferred rather than stated.

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 phrase "existing appointment" implies a prerequisite (the booking must already exist), but the description states no when-to-use guidance, no when-not-to-use condition, and no explicit pointer to book_appointment for new bookings or cancel_appointment for cancellations. Usage is only implied.

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