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

Annotations already establish read-only, non-destructive, closed-world behavior, so the description must add more than safety. It does: "case-insensitive substring match" tells the agent this is literal substring search, not fuzzy or ranked matching, which materially changes how to phrase a query. It does not mention result ordering or how the limit is applied, which keeps it at a 4.

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 the verb and scope, then matching semantics, then filters. No filler and nothing out of order.

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?

An output schema exists, so return values need not be described, and the input surface is small and mostly enum-typed. The remaining gap is pagination/limit behavior and result ordering, which the description leaves silent for a four-parameter search tool.

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 only 25% — query is documented, while limit, status, and platform have no descriptions. The description partially compensates by naming status and platform as optional filters (their enums are self-explanatory), but limit, with its default of 20 and max of 100, is never mentioned in prose. Partial compensation warrants a 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?

"Text-search across the user's posts" states a specific verb (search) and resource (posts), and the parenthetical "(drafts, scheduled, published)" scopes which posts are covered. That implicitly separates it from list_drafts / list_scheduled_posts, though neither sibling is named, so it stops short of a 5.

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?

"Optionally filter by status or platform" gives some usage context, but nothing says when to reach for search_posts versus list_drafts, list_scheduled_posts, or get_post. The 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.