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

Annotations only cover the safety profile (readOnly, non-destructive, closed-world), while the description supplies genuinely additive behavior: it always returns an `as_of` receipt, explicitly refuses to pose as a live feed, abstains instead of guessing when a venue lacks hours, and quantifies coverage at 82%. That is exactly the beyond-annotations context this dimension rewards.

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?

Four sentences, front-loaded with what the tool returns and the provenance constraint, each sentence carrying distinct information (source, staleness receipt, abstention, coverage stat). The coverage-percentage detail is slightly peripheral but still earns its place as a reliability signal.

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?

An output schema exists, so return-value structure needn't be described, and the description still explains the one field that matters semantically (`as_of`). Combined with the abstention behavior and data-freshness disclosure, an agent has everything needed to call and interpret this correctly.

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 required `city` and optional `id`/`name` lookup parameters are already fully documented by the schema. The description adds no format, precedence, or disambiguation guidance beyond that, so the baseline of 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 and resource ('Opening hours for one venue') plus the data source ('the Dim Hour catalog'), which cleanly separates it from venue-detail siblings like get_venue and search_venues. An agent knows exactly what it will receive without opening a sibling 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?

Gives clear context for use: one venue, catalog data, abstains when the venue has no hours, and a caveat to confirm with the venue before relying on it. It never routes the agent to a sibling (e.g., where to get hours another way, or which tool to use for other venue fields), so it falls short of explicit when-not/alternatives.

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