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

Annotations already declare the safety profile (readOnlyHint=false, openWorldHint=true, idempotentHint=false, destructiveHint=false), so the bar is lower. The description adds genuinely useful behavior: media is fetched by the platform at publish time and must remain reachable then, and per-platform validation rejects over-length captions rather than truncating. It does not cover auth requirements, failure modes, or return values.

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 sentences, front-loaded with the core action, then requirements, then media semantics. Every sentence carries distinct information with no 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?

For a non-idempotent scheduling mutation with no output schema, the definition covers platform requirements, media handling, and validation strictness well. It omits scheduling edge cases (past timestamps, per-account partial failure) and any notion of the return value, but nothing essential for a first correct call is missing.

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 the schema already documents all four parameters, including the media URL requirement, extension-based kind inference, and draft behavior. The description mostly reinforces the same material, adding only the publish-time reachability framing. Baseline 3 is appropriate.

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?

Opens with a specific verb+resource ('Schedule a post to one or more connected accounts') and immediately names the media dimension of the operation. An agent knows exactly what this does and how it differs from read-oriented siblings like list_posts or check_draft.

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 platform-level conditions: Instagram/TikTok/YouTube/Pinterest require media, others accept text alone, and omitting a schedule time produces a draft (echoed in the schema). It stops short of naming alternatives or stating when to prefer a draft workflow versus another tool, so it is clear but not fully routing.

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