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

Annotations already declare readOnly/openWorld/non-destructive, so the safety profile is covered. The description adds genuinely new operational context: billing at $0.008 per page, that the 'pages' parameter drives cost, and that get_sentiment carries a surcharge. It stops short of noting rate limits or result-cap behavior.

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?

Four tight sentences: purpose, return payload, filtering options, cost. The most decision-relevant facts (what it does, what comes back, what it costs) are front-loaded and every clause carries 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 no output schema, the description correctly compensates by naming the return fields, and all parameters are covered by the schema. For a paid, open-world search tool it is close to complete, though pagination limits and how sentiment interacts with multi-page billing are left implicit.

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 all seven parameters are already documented with types, defaults, enums and formats. The description reinforces the location_id provenance and the per-page billing tie-in, but adds little syntax or format meaning beyond the schema. 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 and resource ('Search public Facebook posts by keyword') plus scope ('public') and enumerates what is returned (post text, author details, engagement metrics, media). This distinguishes it from page/group-scoped siblings like facebook_page_posts and facebook_group_posts, which cannot search by keyword.

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?

Gives concrete narrowing strategies (date range, sort order, place scoping) and explicitly routes the agent to search_facebook_locations to obtain a location_id, which is a real dependency an agent would otherwise have to guess. It does not state when this tool is the wrong choice versus sibling searches (e.g., search_facebook_pages), so no exclusions are covered.

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