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

Goes well beyond the annotations (readOnlyHint=false, destructiveHint=true, openWorldHint=true): it discloses that changes go live without a publish, that they land 'usually within minutes', that self-referential loops are refused, and that two classes of high-impact edits are gated behind an explicit user-confirmed flag. That is exactly the behavioral context an agent needs for a destructive mutation.

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?

Four tight sentences, front-loaded with the core action and partial-update rule, then escalating to side effects, refusal conditions, and confirmation gating. Every sentence carries information; only the ordering of the confirm rule could be tightened.

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 destructive, open-world mutation with no output schema, it covers the essential unknowns: immediate live effect, error condition (loop refusal), and the human-in-the-loop gate for home-page and external-destination changes. It omits only secondary details such as how deactivating affects live traffic.

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 real meaning the schema does not: partial-update semantics for all provided fields, and the protocol for confirm (only after the user agreed, tied to the two specific risky changes). It does not explain the interaction between active and permanent, but the added value is genuine.

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?

States a specific verb and resource ('Update an existing URL redirect') and immediately clarifies it is a partial update where omitted fields are preserved. This clearly separates it from create_redirect and delete_redirect by name and semantics, though no sibling is named explicitly.

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?

Gives concrete conditions for the risky path: moving source to / or destination to another site requires confirm: true, and confirm should be sent only after the user agreed. Usage context (live immediately, no publish step) is clear, but there is no guidance about when to update vs. create a new redirect or when to deactivate instead.

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