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

Annotations already cover readOnly/idempotent/destructive/openWorld, yet the description still adds non-obvious operational traits: 32 KB payload cap, 60 RPM throttle, L402 payment option (15 sats), demo bypass, and an HTTP 400 failure on invalid input. These are exactly the constraints an agent must know before calling.

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 is front-loaded in the first sentence and every subsequent clause carries information, but the final sentence is telegraphic ('Stateless read-only edge call (max 32 KB, 60 RPM)', 'L402 (15 sats)') and packs several unrelated facts into one dense run-on.

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?

An output schema covers return values and annotations cover safety, and the description fills the remaining gaps: supported standards, size and rate limits, payment/demo access, and error behavior. Nothing an agent needs to invoke it correctly is missing.

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; the description earns an extra point by disclosing that 'feed_standard' defaults to 'rss_2_0', a default not stated in the schema. The remaining parameter mentions (items_json contents) merely restate the schema.

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?

Names a specific verb (transforms) and both input and output resources (JSON item collections / article card arrays → RSS 2.0, Atom 1.0, JSON Feed 1.1). It also names the sibling it is not (crawl_sitemap_urls) so an agent can route without opening either schema.

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?

'Use when syndicating blog articles, product announcements, or changelog cards to RSS readers and AI agents' gives concrete positive triggers, and the sitemap clause explicitly excludes the nearest alternative. Both when-to-use and when-not-to-use are present.

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