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

With annotations already indicating readOnlyHint=false, idempotentHint=true, and destructiveHint=false, the description adds useful context: the data is mutable KV read by the published page, values are arbitrary JSON, and writes are 'scoped to a site you own.' This supplements the annotations without contradicting them.

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 and front-loaded with the trigger condition. Each of its five short sentences contributes a distinct point: use case, operation, storage semantics, value type, and scope, with no filler or redundancy.

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 a fully documented schema, useful annotations, and no output schema, the description provides enough context for an agent to select and invoke the tool correctly. It covers when, what, and scope, and explains the store's role. Minor omissions such as explicit error behavior or overwrite semantics keep it from being fully comprehensive.

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 adds only modest parameter-level context, such as 'value is any JSON' and illustrative examples like 'a price, a deadline, a switch,' which slightly enrich the schema but do not substantially change meaning.

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 verb and resource: 'Sets a key-value item in a site's data store (SnapHost Data).' It also frames the tool's purpose with the use case 'when the page should read a setting or value the owner controls,' which distinguishes it from sibling setters like set_site_slug or set_visibility.

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 opening sentence gives explicit when-to-use guidance: 'Use when the page should read a setting or value the owner controls.' It also explains that the store is 'mutable config/state the published page reads.' However, it does not explicitly name alternatives or state when not to use this tool, so it stops 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.