The YOP MCP Server exhibits significant definition quality gaps across most tools. While tool names follow a consistent naming convention (yeepay_yop_*), descriptions are present but lack LLM-optimized detail. Most critically, input parameters across tools lack explicit type definitions in the visible schema declarations, and output schemas are entirely undocumented. The server provides 10 tools, but only 3 have documented input parameters beyond simple strings. Error handling and parameter validation guidance is absent. Tool compositions show reasonable separation of concerns (read vs. write operations), but parameter descriptions fail to explain constraints, formats, or dependencies.
Output schemas completely undocumented. No tool declares what fields it returns or what structure the response has. LLMs cannot plan downstream tool calls or extract required data without this information.
Parameter descriptions lack format constraints and allowed values. For example, 'algorithm' accepts 'RSA' or 'SM2' but the description does not list these as required enums. 'key_format' accepts 'pkcs8' or 'pkcs1' but is not declared as an enum. This forces LLMs to guess at valid values.
Document the output schema for all tools. Example: 'Returns a JSON object with fields: content (string), language (string, e.g., "markdown"), links (array of objects with url and title).' This allows LLMs to extract data and plan follow-up calls.
Convert algorithm and key_format parameters to explicit enums in the schema. Example: {"type": "string", "enum": ["RSA", "SM2"], "description": "Encryption algorithm. RSA recommended for broad compatibility; SM2 for Chinese payment regulatory compliance."}
Split 'yeepay_yop_product_detail_and_associated_apis' into two tools: 'get_product_detail' (returns product description and usage notes) and 'list_product_apis' (returns associated API endpoint list). Each has a single responsibility.
Clarify 'api_uri' parameter in yeepay_yop_api_detail. Document accepted formats: 'Accepts API path (e.g., /rest/v1.0/aggpay/pre-pay), full docs URL (https://open.yeepay.com/docs-v3/api/...), or legacy URL. Path is preferred and most reliable.'
For cryptographic tools, add explicit warnings about secret handling. Example: 'Note: Base64-encoded private keys should only be passed if generated server-side via gen_key_pair. Never expose user-provided keys in logs or responses.'
Add error handling guidance to download_cert and parse_certificates. Example: 'If download fails with auth_code mismatch, verify the certificate serial_no and auth_code match your CFCA enrollment. If file parsing fails, ensure the certificate is in valid PKCS#12 (.pfx) or DER (.cer) format.'
Tool 'yeepay_yop_product_detail_and_associated_apis' and 'yeepay_yop_api_detail' contain 'and' in the name, signaling multiple responsibilities. These should be split into separate, focused tools.
Parameter descriptions for 'url' in yeepay_yop_link_detail and 'api_uri' in yeepay_yop_api_detail are vague. They accept multiple formats (path, full URL, markdown URL) but do not document this clearly or provide format examples that guide the LLM toward correct usage.
Cryptographic tools (gen_key_pair, download_cert, parse_certificates) accept sensitive data like Base64-encoded private keys and passwords as parameters. While these may be server-side generated, the description does not clarify where secrets originate or how they are protected.
No error handling guidance. Tools do not document what failures look like, what error messages mean, or how to recover. For example, if download_cert fails due to invalid auth_code, the LLM has no guidance on retry or alternative actions.
No input validation rules documented. For example, 'pwd' in download_cert is described as '12~16位' (12 - 16 characters) but this constraint is not enforced or repeated in the description where the LLM reads it.
Tool composition: read-only HTTP tools (yeepay_yop_overview, yeepay_yop_product_overview, etc.) all return markdown strings with embedded links. The description promises 'further detail via yeepay_yop_link_detail', but no guidance on how the LLM should identify which links to follow or when.
Document password length constraints in the parameter description, not just Chinese abbreviations. Example: 'pwd: PFX certificate password (12 - 16 characters, alphanumeric + symbols).'
Add a discovery tool or enhance yeepay_yop_link_detail documentation to guide LLMs on when to extract and follow embedded links. Example: 'Call this tool to fetch details for any link embedded in prior responses. Include the full URL from the markdown link destination.'
Add 'idempotentHint' or 'readOnlyHint' annotations to schema definitions for tools that modify state vs. read-only queries. This helps LLMs understand retry safety.
Validate input parameters at tool entry. For 'algorithm', reject values other than 'RSA' and 'SM2' with a clear message: 'Invalid algorithm: "SM4". Must be RSA or SM2.'
Document pagination and result limits for tools returning large content (e.g., yeepay_yop_api_detail). Example: 'Returns up to 5000 characters of documentation. For longer APIs, use yeepay_yop_link_detail to fetch the full spec page.'