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

Adds real context beyond the readOnly/openWorld annotations: the target must be a public post, the response carries text and engagement counts, and each call costs 1 credit. It does not explain caching behavior or what happens for private/deleted URLs.

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?

Three short sentences, front-loaded with what the tool returns, then the cost. No filler and nothing to trim.

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 annotations covering the safety profile and no output schema, the description supplies the essential shape of the result (text plus engagement counts) and the credit cost. The only meaningful gap is the undocumented cache_max_age parameter and its effect on freshness or pricing.

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 50%: url is documented, cache_max_age is not. The description reinforces that url is a full post/video/reel URL but adds nothing about cache_max_age, leaving half the parameters explained only by a bare schema entry. Baseline 3 given the partial coverage.

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 resource (one public Facebook post, video, or reel) fetched by URL and returned with text and engagement counts. It is distinguishable from facebook_pagePosts (lists) and facebook_postComments (replies), though it never names those siblings to sharpen the boundary.

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 phrase 'One public Facebook post... by URL' implies when it applies (single-item lookup by URL, public content only), but there is no explicit routing guidance such as using facebook_postTranscript for transcript or facebook_postComments for replies, and no stated exclusions.

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