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

Annotations already declare readOnlyHint, idempotentHint and closed-world behavior, so safety needs no restating. The description adds genuinely non-structured behavior: results are ordered newest first, status values are explained (including that the first three are the free sitemap import/review stages), sample_mode distinguishes a re-scan from a first scan, and an empty page is explicitly not evidence that no scans exist. Only pagination/limit behavior is left to the schema.

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?

Purpose and ordering are front-loaded, which is correct, but the third sentence is a single sprawling enumeration of nine return fields with parenthetical status definitions that is hard to scan. Given there is no output schema the enumeration earns its place, but it could have been structured as a list rather than one run-on sentence.

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 carries the full burden of describing return shape and it does so, field by field, including counts, template count, ids and dates. Status semantics and the empty-page caveat close the remaining interpretive gaps for a four-parameter list tool.

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 50%: limit and cursor are documented in the schema, while status and client_id are bare. The description compensates well for status by listing all nine lifecycle values and their meanings, and labels client_id as a filter. It adds no meaning for client_id beyond being a filter, which keeps it from a 5.

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 gives a specific verb and resource ("Lists the Accessibility Scans") plus scope ("in the connected account") and ordering ("newest first"). The resource is distinct from every sibling (list_citation_scans, list_crawlability_scans, list_diagnostics), and a second sentence defines what an Accessibility Scan actually is, so the agent knows what records it will get.

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 description names the two filters (client_id and status) and explains how to interpret an empty result, which is real context for calling the tool. It never contrasts this with get_accessibility_scan or get_run_status, so the choice between listing and fetching a single scan is left to inference from the names.

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