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

With no annotations provided, the description carries full behavioral disclosure burden. It explicitly states the flat 2-credit cost, that empty results and failures are never charged, and the cache semantics (cache=true gives a free 24h hit, default is always fresh). These are the key behavioral traits an agent needs to make cost-aware decisions, and they are communicated clearly.

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 short and front-loads the purpose and output. However, it contains a redundant duplicate: 'Flat 2 credits. Costs 2 credits.' — the same fact stated twice in adjacent fragments. Otherwise every sentence earns its place, covering output, cost, failure pricing, and cache behavior.

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?

For a simple 3-parameter tool with no output schema, the description covers purpose, cost, caching, and a partial output shape (id + lat/lng). It is complete enough for an agent to call the tool correctly. It could be stronger by describing the response structure in more detail, but the minimal output hint is sufficient for this use case.

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 no new parameter meaning beyond the schema: it repeats the cache cost/behavior already documented in the schema and does not add details for 'q' or 'limit'. The useful cost-on-failure note is behavioral rather than parameter-specific.

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 opens with a specific verb and resource: 'Disambiguate city names into Marketplace hubs — id + lat/lng.' This clearly distinguishes the tool from siblings like facebook_marketplace_search and facebook_marketplace_item, which handle listings rather than location resolution. It also names the key output fields, leaving no ambiguity about what the tool produces.

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 intended use case is implied by 'Disambiguate city names into Marketplace hubs' — an agent can infer it should be called when a city string needs resolving to a hub ID. However, it never explicitly states when to prefer this over the sibling search tools, nor does it mention any exclusions or preconditions. The guidance is present but left to inference.

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