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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds real beyond-annotation behavior: a holder-only limitation and the statement that other guest details cannot be amended, which materially constrains the call.

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?

The overview is front-loaded, but four markdown sections restate the same content: 'When to Use' bullets repeat the overview, 'What You Get' and 'Quick Start' repeat the editable-fields/quick-start information again. Roughly half the text is redundant padding for a 3-parameter tool.

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?

With no output schema, the description usefully states what is returned (a confirmation and the updated booking). It covers the key limitation and required inputs, though it never mentions idempotency and misstates the editable field set by excluding phone.

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 67% with a documented nested holder object, so the schema carries most parameter meaning and baseline 3 applies. The description enumerates editable fields but actively omits 'phone' (present in the schema) while claiming 'other guest details cannot be amended', which is a mild inconsistency rather than added clarity.

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 Overview states a specific verb+resource (update guest information - name and email - for an existing booking), which is clear and distinct from read siblings like get_bookings_bookingid. It does not name the close sibling put_bookings_bookingid or explain how 'amend' differs from the full update, so it stops short of full sibling differentiation.

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?

A dedicated 'When to Use' section gives concrete contexts (typo fixes, email updates, support requests), which is more than implied usage. However it offers no exclusions or alternatives (e.g., when to use put_bookings_bookingid instead), so it stays at clear-context without guidance.

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