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

Goes well beyond the annotations: it discloses the 1,000-per-call cap, that re-adding an address replaces its destination (consistent with idempotentHint=true), and the propagation behaviour — live within a minute or two on a published site, otherwise applied at publish. That timing and overwrite semantics are exactly the kind of context annotations cannot convey.

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 purpose is front-loaded and every sentence carries information — field semantics, limits, replacement rule, propagation timing. It is dense but not padded; a bulleted or line-broken layout for the per-field rules would have made it marginally easier to scan.

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 mutating bulk tool with annotations covering the safety profile, the description covers limits, defaults, overwrite behaviour and propagation. It does not say what happens on partial failure (e.g. one invalid entry among many) or whether the created redirects are returned, which matters for a 1,000-item batch.

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% and the nested `from`/`to`/`status` properties carry no descriptions at all, so the description does the heavy lifting: `from` accepts a full old URL and preserves an identifying query string, `to` may be a local path or an external URL, and 301 is the default with 302/307/308 as alternatives. That adds real meaning the schema cannot express (the default is not encoded anywhere).

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 opening sentence states a specific verb+resource outcome ("Send old addresses to new pages so links ... keep working") and the body makes clear this is a bulk-add operation (up to 1,000 per call). It does not explicitly name the near neighbours it must be distinguished from (update_redirect, remove_redirects, map_old_site_links), so an agent still has to infer the split from the name.

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?

Usage is implied by the framing ("send old addresses to new pages") and one parameter-level rule is given ("use 301 unless the user asks otherwise"). There is no explicit statement of when to prefer this over update_redirect for an existing mapping, or how it relates to map_old_site_links.

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