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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely new operational context: the credential cost of '10 points per returned record', which is exactly the kind of billing signal annotations cannot express, plus the concrete shape of records returned including BuySell price and location fields.

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 tight sentences: purpose and return fields first, cost last. The field enumeration is long but earns its place because there is no output schema to document the record shape. Slightly dense, but zero filler.

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 discloses the return fields (text, author, time, reaction/comment/share counts, attachments, top comments, BuySell price and location) and the per-record cost. What is missing is routing guidance against the several other Facebook tools, which matters in a sibling set this large.

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 the schema already explains url, sort, max_items and newer_than in detail including enum meanings and defaults. The description adds nothing about parameter behavior beyond echoing the BuySell fields, which loosely maps to the CHRONOLOGICAL_LISTINGS sort option. Baseline 3 applies when the schema carries the load.

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 states the resource (posts from public Facebook groups) precisely enough to distinguish it from run_facebook_posts or run_facebook_search, and enumerates returned fields. The verb is implicit rather than stated ('Posts from...'), and the sibling distinction is by resource noun only, but an agent can identify the tool correctly.

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 only usage constraint given is 'public' groups, which does rule out private groups. There is no guidance on when to pick this over run_facebook_posts, run_facebook_comments, or run_facebook_search, and nothing about selecting sort modes like CHRONOLOGICAL_LISTINGS over the plain chronological default.

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