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Sandbox management via Model Context Protocol - provides tools for creating, managing, and executing code in isolated sandbox environments with support for multiple programming languages
The server defines 5 filesystem tools with clear naming (upload_file, download_file, list_files, enhanced_upload_file, enhanced_download_file). All tools have descriptions and input schemas with proper types and required fields. However, definitions lack depth in several areas: (1) Descriptions are concise but generic, they state WHAT but lack WHEN/WHY context for LLM selection. (2) Parameter descriptions are minimal; e.g., 'sandbox_id' is described only as 'The unique identifier of the sandbox' without guidance on format or lookup. (3) Output schemas are not documented, callers cannot see what fields the tools return, forcing the LLM to guess. (4) Error handling is not described, no recovery guidance for common failures like permission denied, file not found, or sandbox not found. (5) Tool composition is problematic: upload_file and enhanced_upload_file perform nearly identical operations (with enhanced adding backup/overwrite), creating ambiguity about which to call. Similarly, download_file and enhanced_download_file differ only in size limits and offset support. The rubric expects clear differentiation or unified interfaces. (6) No mention of idempotency or retry semantics, critical for file operations. (7) Security considerations are absent from descriptions (e.g., path traversal protection, sandbox isolation guarantees).
Downloads a file from the sandbox environment
Downloads a file from the sandbox environment using secure container filesystem
Uploads a file to the sandbox environment using secure container filesystem with backup and audit
Lists files and directories in the sandbox environment
Uploads a file to the sandbox environment using secure container filesystem
Duplicate/overlapping tools cause ambiguity. upload_file and enhanced_upload_file are nearly identical; the LLM cannot determine which to call without understanding internal differences (backup, force_overwrite flags). Same issue with download_file vs enhanced_download_file (size limits, offset parameters). Rubric pattern:tool requires each tool to do exactly one thing with clear differentiation.
Output schemas are not documented. Callers see input definitions but have no schema for what these tools return. Cannot determine if upload_file returns a file_id, timestamp, size, or other metadata. Rubric pattern:tool requires documented return types for downstream tool chaining and LLM planning.
| Scored | Grade | Overall | Spec posture | Rubric |
|---|---|---|---|---|
| 2026-09-22 | F | 48 | 2026-07-28+ | v2 |
| 2026-03-09 | F | 21 | - | v1 |
Descriptions lack WHEN/WHY context. Each tool's description states only what it does in 2 - 3 sentences (avg ~50 chars). No guidance on when to use it vs similar tools, prerequisites, or failure modes. Rubric baseline expects 50 - 200 chars with clear selection context. Example: 'Uploads a file to the sandbox environment using secure container filesystem', does not explain when to call vs enhanced_upload_file, or what happens if the file exists.
Parameter descriptions are generic and lack actionable format guidance. Example: 'sandbox_id' described as 'The unique identifier of the sandbox', no clarification of format (UUID? hex? integer?), how to obtain it, or if lookup is required. Rubric requires descriptions that answer: What does it control? What format? What values are valid? This forces LLMs to guess or make invalid calls.
No error handling guidance. Tool descriptions do not state how failures are communicated (HTTP status codes, structured error objects?) or what the LLM should do on failure. Example: If sandbox_id is invalid, should the agent retry, search for valid IDs, or ask the user? Rubric pattern:recovery-guide requires actionable error responses.
Idempotency and retry semantics not specified. File uploads may be retried on network failure, if a retry succeeds but the original also completed, does the file get overwritten or appended? Rubric pattern:idempotent-operation requires clear semantics for idempotency, especially for persistence operations.
Security considerations absent from descriptions. Tools operate on sandbox filesystems but do not document: (1) path traversal protection (can LLM pass '../../../etc/passwd'?), (2) sandbox isolation guarantees, (3) permission model. Rubric pattern:permission-gate and pattern:secret-injection require explicit security boundaries in tool descriptions.
Parameter 'encoding' uses enum ['base64', 'utf8'] but lacks guidance on when to use each. LLMs may default to utf8 and fail silently on binary data. Description should explain: 'Use base64 for binary files (images, archives); utf8 for text. Invalid encoding will produce corrupted output.'
enhanced_download_file parameters (max_size, offset, length) lack clear semantics. If max_size=1MB and file is 5MB, does the tool: (1) fail, (2) return the first 1MB, (3) return an error with guidance to increase max_size? No default behavior clarified. Offset and length also lack explanation of mutual exclusivity or interaction.