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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial non-obvious behavior: statelessness, a 32 KB payload cap, 60 RPM throughput, a demo bypass, an L402 payment of 10 sats, and HTTP 400 on invalid input. The only shortfall is that it doesn't say what happens at the rate limit (429 vs queue) or whether the sats charge applies per call.

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?

Front-loaded with purpose, then usage, then operational constraints in a tight single paragraph. The third sentence packs several unrelated facts (size cap, rate limit, demo, L402, error code) into one clause chain, which is dense but every element is relevant to calling the tool correctly.

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 an output schema present, the description needn't explain return values, and it covers the remaining gaps an agent needs: auth/payment path, size and rate limits, failure mode, and the default audit scope. Complete for a single-required-parameter read 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 100%, so the baseline is 3; the description earns above that by disclosing 'audit_level' defaults to 'comprehensive_audit' and implicitly scoping 'html_content' to a raw HTML string. It never mentions 'target_keyword', leaving that parameter entirely to 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?

States a specific verb ('Audits') plus the exact resources checked (heading structures, title lengths, meta descriptions, alt tags, OpenGraph) and the output artifact (health score). It also names the sibling it is not (scrape_readable_article), so an agent can discriminate 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?

Explicitly enumerates three triggering scenarios (auditing landing pages, pre-publish SEO compliance, crawl friendliness) and names the alternative tool with the condition that selects it ('for extracting article bodies, use scrape_readable_article instead'). Nothing is left to inference.

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