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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds behavior annotations do not: the data source is the Silex blocklist shared with its iPhone app and browser extension, and sub-domains match their parent — a matching rule that materially affects result interpretation. It omits any note on coverage limits (false negatives for unlisted sites) or response shape.

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 what the tool does and followed by the matching rule and the usage trigger. No filler, no repetition of the title, and the most decision-relevant facts come first.

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?

There is no output schema, so the description carries the burden of explaining what comes back, and it never says whether the result is a per-site boolean, a list of matches, or a hit count — an agent must call it blind. It is otherwise complete on scope and matching semantics for a simple single-parameter lookup.

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% with an example and min/max items, so the single parameter is fully documented in structured form. The description only implies it accepts web addresses/URLs in batch via phrasing; it adds no new syntax or normalization guidance (e.g. whether scheme or www. is stripped). Baseline 3 applies.

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 (checks) and resource (web addresses against a gambling blocklist) with exact scale (~294,000 domains) and source. It reads clearly as a lookup/verification tool, which an agent can immediately distinguish from the sibling block_gambling, a mutation tool.

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 final sentence gives explicit triggering contexts: someone asks whether a site is a gambling/betting site, or whether a blocker would stop it. It lacks an explicit negative boundary or a named alternative (e.g. "to add a site to the blocklist use block_gambling instead"), so routing is clear but not fully closed.

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