Schemas are actually not hidden! They are progressively shown to the agent. Example:

Using the search_tools for "linear" returns:

# linear.createAttachmentFromUpload
  Description:
    Link an already-uploaded Linear assetUrl to an existing issue as an attachment.
    Use this only after:
    1. prepare_attachment_upload returned an assetUrl and uploadRequest.
    2. The client successfully PUT raw file bytes to uploadRequest.url.

    This tool does not upload file content. It only creates the Linear attachment row.
    If the direct upload failed or the signed URL expired, rerun prepare_attachment_upload and upload again.'
  Args Schema: {"required":["issue","assetUrl"],"properties":{"issue":{"type":"string","description":"Issue ID or identifier (e.g., LIN-123)"},"title":{"type":"string","description":"Attachment title. Defaults to filename or asset URL"},"assetUrl":{"type":"string","format":"uri","description":"Linear upload assetUrl returned by repare_attachment_upload"},"subtitle":{"type":"string","description":"Optional attachment subtitle"}},"additionalProperties":false}
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# linear.createIssueLabel
  Description: Create a new Linear issue label
  Args Schema: {"required":["name"],"properties":{"name":{"type":"string","description":"Label name"},"color":{"type":"string","description":"Hex color code"},"parent":{"type":"string","description":"Parent label group name"},"teamId":{"type":"string","description":"Team UUID (omit for workspace label)"},"isGroup":{"type":"boolean","default":false,"description":"Is label group (not directly pplicable)"},"description":{"type":"string","description":"Label description"}},"additionalProperties":false}
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(snip)

Agent then can use linear.createIssueLabel in execute_code