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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false. The description adds useful behavioral context beyond that: the vocabulary is 'closed,' the values are 'today's live' values, and they are scoped 'across published venues.' This meaningfully explains freshness and scope without contradicting the annotations.

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?

A single dense sentence front-loads the primary purpose and immediately follows with an explicit sibling-route alternative. Every clause carries useful information; there is no filler or repetition of schema content.

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?

With an output schema present, no parameters, and annotations covering safety and world assumptions, the description fully supplies the remaining context: what the values are for, their freshness, and how this tool differs from destination_facets. Nothing an agent needs to select and invoke it correctly is missing.

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?

The tool has zero parameters and the schema is empty, so the baseline is 4. The description adds contextual meaning about what the no-parameter call returns, which is sufficient given there is nothing to configure.

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 names the exact resource—the closed VENUE facet vocabulary plus today's live cuisine, price_band, and neighbourhood values—and states what those values are for: the exact values search_venues' matching filters accept. It also explicitly distinguishes this tool from destination_facets, so an agent can tell them apart immediately.

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?

It clearly identifies when to use this tool (for venue facet filter values across published venues) and gives an explicit exclusion: 'for a destination's areas, categories and tags call destination_facets instead.' This gives the agent a concrete routing decision without needing to open schemas.

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