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

Goes well beyond readOnlyHint/openWorldHint: discloses that results are persisted to the user's history, that the call costs 20 credits with a 2-credit cached rate for posts read in the last 6 hours, and that transcripts fall back to automatic audio transcription when native captions are absent. That cost/caching/fallback information is exactly what an agent needs before invoking.

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?

One dense paragraph that front-loads the verb and platform list, then outputs, then usage trigger, then cost. Every clause carries information, though the parenthetical output enumeration is heavy and the cost note would read better as a trailing sentence than nested in a parenthesis.

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?

No output schema exists, so the description correctly carries the burden of describing return contents, and it does so thoroughly. Minor gap: no note on failure behavior for unsupported or private links, which matters for an openWorld tool scraping external platforms.

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 url, niche and include_images are already documented and the schema even carries the default for include_images. The description adds no semantics for niche (fit score) or include_images beyond confirming images are returned, so the schema is doing the heavy lifting — baseline 3.

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 ("Reads any post by its link") and immediately enumerates the supported platforms and the exact artifacts returned (transcript, slide text, comments, metrics, mind map, Viral Score). An agent can tell this apart from a generic fetch without opening the schema.

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?

Explicitly names the triggering conditions: the user pastes a post link, or asks to summarize, understand, study or compare a post. However, it never mentions the closest-looking siblings (analyze_post, analyze_creator, transcribe_video, read_ad), so an agent must infer the boundary itself.

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