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

This description discloses several behavioral traits beyond the annotations: it reveals the existence of a stored snapshot (state), explains caching behavior ('allow cache reuse'), and states a clear limitation ('does not execute JavaScript or bypass access controls'). With annotations that only hint at side effects and external calls, the description adds substantial context about how the tool operates.

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?

The description is concise at four sentences, with the main purpose front-loaded and no filler. Every sentence contributes either core purpose, constraints, or parameter guidance. It is efficient and well-structured.

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?

Given the tool's moderate complexity (2 params, 1 required) and the presence of an output schema, the description is complete. It covers purpose, constraints, and parameter usage. The output schema handles return value details, so nothing additional is needed.

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%, so the baseline is 3. The description's parameter guidance ('Pass url as an absolute public HTTP(S) URL' and 'Keep fresh=false to allow cache reuse') largely repeats what the schema already says (pattern and descriptions). It adds minimal value beyond the schema, so a 3 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?

The description clearly states a specific action and resource: 'Compare the normalized content hash with the previous stored snapshot.' This unambiguously distinguishes the tool from related siblings like web.url.hash (which likely just computes a hash) or web.url.changed (which may detect changes differently). The verb 'compare' and the reference to a 'stored snapshot' make the purpose fully understandable.

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 provides explicit when-not guidance: 'Use only for public HTTP(S) resources; it does not execute JavaScript or bypass access controls.' It also gives parameter usage advice (fresh=false vs true). However, it does not name alternative tools or explicitly state 'use X when you need Y,' so it falls just short of a 5.

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