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

With annotations only covering readOnly/openWorld, the description carries real weight: it discloses the residential-proxy sourcing, the logged-out page truncation of posts (~10), the per-call price of $0.002 USDC via x402 with supported chains, and that failed calls are free. That is exactly the operational context an agent needs before calling a paid scraper.

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?

Two sentences, both dense but front-loaded: the data payload comes first, the sourcing/limits/pricing second. No filler, and each clause (proxy, truncation, price, free failures) adds distinct decision-relevant information.

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, return values needn't be explained, yet the description still summarizes them along with cost and data-quality caveats — close to complete for a read-only paid fetch. The only gap is the absence of any explicit alternative-tool routing for agents that actually want search or replies.

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%, so both parameters are already documented, including the handle format and the 0–20 limit range with a default of 10. The description only loosely echoes the post count ('about 10') and adds no syntax or formatting guidance beyond the schema, so baseline 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+resource (fetch a Threads profile by handle) and enumerates exactly what is returned: name, verified flag, bio, followers, bio links, and ~10 recent posts with engagement metrics. This is clearly distinguishable from siblings like social_threads_search (query-based) and social_threads_replies (reply threads).

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 usage (look up a public Threads profile page by handle) and notes that logged-out pages only expose a limited number of posts, which sets expectations. However, it never explicitly says when to choose this over social_threads_search or social_threads_replies, leaving the routing decision to inference.

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