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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower. The description still adds real behavioral context beyond them: the change set is computed as a diff between the two most recent crawls and is scoped to six specific SEO attributes. It does not cover result limits, ordering, or behavior when fewer than two crawls exist.

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 sentence that front-loads the operation and the comparison window, then lists the change scope in a compact parenthetical. No filler, no restatement of the name or title.

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 must convey what comes back, and it does by naming the six compared attributes plus the two-crawl comparison basis. It leaves unstated the response shape (per-URL diff? counts?), ordering, and the zero/one-crawl edge case, so it is strong but not fully self-contained.

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% (site_id is documented as 'UUID of the site'), so the schema carries the parameter semantics. The description adds nothing about the parameter, so the baseline 3 for a schema-documented single-parameter tool is appropriate.

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 ('Recent SEO changes detected') and enumerates the change categories (title / meta / h1 / canonical / indexability / status code), so an agent can distinguish it from siblings like get_site_audit or get_scan_pages. It stops short of naming an alternative, so it is clear but not sibling-differentiating.

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 'between the two most recent crawls' implies the precondition (at least two completed crawls) and frames this as a delta tool rather than a snapshot, which is useful implicit guidance. However, it never states when to pick this over get_site_audit / get_scan_pages / get_score_history, and no exclusions are given.

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