Multi Upload Tool

validate_post

Read-only

Dry run of create_post: takes the same arguments and runs the same checks (account status, plan, daily caps, monthly quota, queue room, caption and title limits, required platformSettings, scheduling window) without publishing anything. Call it before create_post on any batch, or whenever unsure — a post rejected here would otherwise fail later, sometimes hours later for scheduled posts. mediaUrls are not downloaded: file format, size and duration are only checked when the post is actually published.

Returns: { valid, errors: [{ accountId, platform, error }], targets: [{ accountId, platform, scheduledFor }] }. An error with accountId null applies to the whole batch.

Input Schema

Name	Required	Description
`text`	No	Post text / caption
`status`	No	Create the post without publishing it: 'draft' (you or the user keeps editing) or 'pending_approval' (a human approves it in the app or through create_review_link). In a team that requires approval, a member's posts are always 'pending_approval'.
`mediaUrls`	No	Public http(s) URLs of images or videos to attach
`overrides`	No	Per-network or per-account variants: keys are a platform name ("bluesky") or an accountId, values { text?, title? }. An accountId key wins over its platform, which wins over the shared text. Use it when one caption cannot fit every network (Bluesky 300 chars vs YouTube 5000).
`accountIds`	Yes	Connected account ids from list_accounts
`scheduledAt`	No	ISO 8601 with timezone offset — omit for immediate publish
`idempotencyKey`	No	Unique key for this post (e.g. a UUID). Reusing it within 24h returns the first result instead of publishing again.
`platformSettings`	No	Per-platform required settings. See tool description and get_platform_capabilities.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedOct 18, 2026
- addedInput schema / properties / platformSettings / properties / instagram / properties / coverUrl
```
Added value: +{
+  "format": "uri",
+  "type": "string"
+}
```
Changed1 schema field changedOct 17, 2026
- addedInput schema / properties / platformSettings / properties / youtube / properties / thumbnailUrl
```
Added value: +{
+  "format": "uri",
+  "type": "string"
+}
```

Changed9 schema fields changedOct 15, 2026

addedInput schema / properties / accountIds / items / minLength
```
Added value: +1
```
addedInput schema / properties / idempotencyKey / minLength
```
Added value: +1
```
addedInput schema / properties / overrides / additionalProperties / properties / text / maxLength
```
Added value: +63206
```
addedInput schema / properties / overrides / additionalProperties / properties / title / maxLength
```
Added value: +500
```

addedInput schema / properties / overrides / propertyNames

Added value: +{
+  "maxLength": 64,
+  "minLength": 1,
+  "type": "string"
+}

changedInput schema / properties / scheduledAt / description

Previous value: -"ISO 8601 — omit for immediate publish"New value: +"ISO 8601 with timezone offset — omit for immediate publish"

addedInput schema / properties / scheduledAt / pattern

Added value: +"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$"

addedInput schema / properties / text / default
```
Added value: +""
```
addedInput schema / properties / text / maxLength
```
Added value: +63206
```

First observedOct 8, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Goes well beyond readOnlyHint=true by enumerating the checks performed and, critically, the limit of the validation ('mediaUrls are not downloaded: file format, size and duration are only checked when the post is actually published'). That caveat is exactly the kind of non-obvious behavior an agent cannot infer from structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Three compact blocks — what it does, when to call it, what it returns — front-loaded with the dry-run framing and no filler. Every sentence carries distinct information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, yet the description supplies the return shape ({ valid, errors, targets }) and even explains the accountId-null edge case. Combined with the check list and caveats, nothing needed to call it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is already 100%, so the baseline is 3. The description still adds meaning by flagging that required platformSettings are validated and that mediaUrls are accepted but not verified, which steers parameter usage more than the schema alone does.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource ('Dry run of create_post') and immediately scopes it by listing the exact checks it performs, so an agent knows precisely what it does. It is explicitly differentiated from the sibling write operation it mirrors.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit when-to-use guidance ('Call it before create_post on any batch, or whenever unsure') plus the consequence of skipping it ('a post rejected here would otherwise fail later, sometimes hours later for scheduled posts'), which names the alternative and the selection condition.

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

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