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

With no annotations, the description carries the full load and does well: it discloses the return shape (changed=true/false plus added/removed lines), the payment requirement and network (USDC on Base eip155:8453 via x402 in params._meta), and the HTTP transport. It omits rate limits, error behavior, and whether state persists server-side between polls.

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?

Three tight sentences, front-loaded with purpose and batch scope before pricing and transport details. Pricing/payment detail earns its place given x402, though the raw endpoint URL is filler for an agent already holding the tool binding.

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?

No output schema, and the description does compensate by describing the diff response, so an agent knows what comes back. But with no annotations and four undocumented parameters including two behavior-defining enums, an agent still cannot confidently construct a correct call from the description alone.

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 only 33% — only 'urls' and 'url' are documented in the schema. The description explains no parameters at all, leaving the semantically loaded enums (mode: text/markdown/meta/links, baseline: stored/watch) and prev_hash/context_lines undefined anywhere, and 'baseline' in particular determines whether a diff is even possible.

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+resource ('Monitor public web pages for changes') and immediately scopes the batch variant with 'One call checks many URLs', which lets an agent separate it from the single-URL sibling. It never names chgwatch__diff explicitly, so differentiation is inferential rather than stated.

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?

'so alert agents pay per poll instead of per page' gives a cost-based rationale for batching, which implies when to pick this over per-page polling. However, there is no explicit 'use chgwatch__diff for a single URL' routing, and no exclusions or prerequisites (auth, rate limits) are stated.

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