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

The annotation readOnlyHint=true already communicates that this is a safe read operation. The description adds valuable behavioral context by explaining that the tool returns a list of filter vocabularies (cuisines, tags, etc.) and that these are tied to the city's catalogue. It does not contradict annotations, and the extra detail about filter value validity is a useful addition.

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 a single, dense sentence that front-loads the core return values and then provides a clear usage directive ('Call this before filtering...'). There is no fluff; every clause serves a purpose, making it both concise and effectively 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 has one simple parameter, no output schema, and the description covers the return content and usage timing, it is fairly complete. However, it doesn't explicitly state that the tool returns no venue list itself (only the count), which could confuse an agent expecting full venue data, but sibling tools like search_venues likely cover that. This minor gap prevents a 5.

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 coverage is 100% for the single parameter 'slug', and the schema description states it comes from list_cities. The description reinforces this by implying the slug identifies a specific city. While it doesn't add new syntax details, the 'list_cities' reference for obtaining the slug is helpful, and the absence of multiple parameters lowers the need for extensive semantic expansion.

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 the resource ('one city's guide') and the specific data returned (editorial blurb, venue count, filtering vocabulary). It distinguishes itself from siblings by focusing on the city-guide metadata needed to construct filters, which is not covered by 'get_venue' or 'search_venues'.

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 explicitly says to call this tool 'before filtering' so that filter values come from the actual catalogue (areas, cuisines, etc.) instead of guesses. It implies this is a prerequisite to other tools that perform filtering, effectively stating when to use it in a workflow.

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