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

Annotations already establish the safety profile (readOnlyHint=false, destructiveHint=false, openWorldHint=true), so the bar is lower. The description adds non-trivial behavioral context the annotations cannot express: the future-datetime requirement, platform-specific validation gates, and the fact that IDs must be sourced from other tools before calling. It does not describe scheduling vs. immediate-publish semantics or failure behavior, so it falls short of a 5.

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?

Front-loaded with the core action and ID provenance, then a clearly delimited PLATFORM NOTES block; every line carries a distinct constraint. Minor redundancy (YouTube/TikTok media requirements restate schema-level information), keeping it just short of optimal.

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 14-parameter tool with nested objects and no output schema, the description supplies the cross-parameter rules that decide whether a call will succeed per platform, plus the datetime constraint. Remaining gaps (isStory, utmCampaign, shortenLinks, X-specific fields) are already documented in the schema, so coverage is adequate though not exhaustive on side parameters.

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 baseline is 3. The description goes beyond the schema by documenting cross-field dependencies the schema cannot express — which parameter combinations each platform demands and where socialAccountId, mediaIds, and boardId originate. That is genuine added meaning over per-parameter text.

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+resource ('Create and schedule a new social media post') and scopes it to exactly one social account, which distinguishes it cleanly from edit_post, delete_post, and cancel_post. It also names the sibling tools that supply its inputs (list_social_accounts, upload_media_from_url, list_media), so an agent can place it in the workflow without opening other schemas.

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 explicit context for use: per-platform prerequisites (Instagram needs media, YouTube needs video + title, Pinterest needs boardId) and the constraint that scheduledAt must be a future ISO 8601 datetime. It routes the agent to the correct sibling tools for obtaining IDs. It stops short of explicit when-not/what-to-use-instead guidance for create vs. edit paths, so it is clear but not exhaustive.

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