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

Adds substantial behavior beyond the annotations: Threads handles are derived from the Instagram handle at no extra cost, Meta rounds IG/Threads counts (both rounded integer and display string returned), and Facebook is best effort because Meta serves a login wall, so 'blocked' is a normal answer and never a zero. It also discloses auth needs (APIFY_TOKEN) and per-call credit consumption. The one tension is that the description says 'Read only' while readOnlyHint=false; that annotation most plausibly reflects credit spend and cache writes rather than data mutation, so this is a nuance to resolve rather than a flat contradiction.

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?

Five sentences, zero filler, and the primary outcome is front-loaded before the caveats. Each sentence contributes a distinct fact: scope, Threads derivation, rounding behavior, Facebook reliability, and auth/cost — nothing repeats the schema or the annotations.

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 no output schema, the description usefully characterizes the returned row (flat, Clay-ready, follower and post counts, rounded plus display string) and covers auth, cost caps, caching via skipCache, and the Facebook-blocked edge case. It stops short of stating what the row looks like when no profile is resolved at all, which is the remaining unspecified outcome for a 7-parameter discovery tool.

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 every parameter (handle, platforms, skipCache, company_name, company_domain, max_charge_usd, includeFollowerCounts) is already documented in the input schema, which sets the baseline at 3. The description adds only the derived-Threads insight and the rounded/display-string return detail, neither of which illuminates a parameter's semantics beyond what the schema says.

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: 'Resolve a company domain to its Instagram, Threads and Facebook accounts with follower and post counts, as one flat Clay ready row.' The output shape and the three platforms are named up front, so an agent knows exactly what it gets back without opening the schema. No siblings exist, so no differentiation is needed.

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 implies when the tool is appropriate (resolving social presence from a domain) and provides a prerequisite ('requires an APIFY_TOKEN and consumes Apify credits per call'), but it never states when not to use it or what alternative exists. The strongest routing guidance — dropping Facebook, supplying a handle to skip discovery — lives in the parameter descriptions rather than the tool description. Adequate but not explicit.

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