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Jambozx

OnlineCyberTools MCP (280+ filterable tools)

security_jwt_generator_validator

Read-onlyIdempotent

Decode, validate HMAC signatures, sign HMAC tokens, and build JWT claim payloads. Supports preset and standard claims, with configurable expiration and audience checks.

Instructions

JWT Decode, Validate, Sign and Claim Builder. Decode, validate (HMAC), HMAC-sign, and assemble JSON Web Tokens (RFC 7519) plus list claim-set presets and standard-claim docs, all from a single operation switch. Unlike encoding_decoding_jwt, which only decodes/inspects, this tool also verifies HMAC signatures (HS256/HS384/HS512), recomputes a signature to mint a token, and builds claim payloads with iss/sub/aud/exp/nbf/iat/jti. Asymmetric algorithms (RS/ES/EdDSA) are decoded but NOT verified or signed server-side. Time is never read from the clock: pass an explicit now (epoch seconds) for exp/nbf/iat comparisons and deltas, so identical input yields identical output. Runs locally via a bundled pure-JS HMAC implementation: read-only, non-destructive, contacts no external service, and is rate-limited (30 requests/minute for anonymous callers). Returns success, the echoed operation, and an operation-specific result object.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
operationYesAction to run. decode: parse a token (no signature check). validate: verify an HMAC signature plus claim validity. signHmac: mint an HMAC-signed token. assembleClaims: build a claim payload. presets: list curated claim-set presets. standardClaims: list RFC 7519 registered-claim docs.
tokenNoCompact JWS string (header.payload.signature). Required for decode and validate; ignored otherwise.
secretNoShared HMAC secret (UTF-8) used by validate to recompute the signature. Required for HMAC validation; ignored otherwise.
nowNoCurrent time in epoch seconds for exp/nbf/iat checks on decode. Omit to compare against epoch 0 (relative-time strings only).
optionsNoClaim-check settings for validate (ignored for other operations).
inputNoOperation payload for assembleClaims (claim fields) or signHmac (token parts).

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
successNoAlways true on a 2xx response.
operationNoThe operation that was executed.
resultNoOperation-specific output. decode: {header,payload,signature,raw,claims,warnings,error}. validate: {valid,errors,header,payload,signatureValid,claimsValid}. signHmac: {token,header,payload}. assembleClaims: {claims,warnings}. presets: {presets[]}. standardClaims: {claims[]}.
Behavior4/5

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

The description adds useful behavioral context beyond annotations: it discloses local pure-JS implementation, read-only/non-destructive nature, no external service contact, rate limiting (30 req/min), and explicit now parameter for deterministic behavior. Annotations already indicate read-only and idempotent, so the description provides additional detail without contradiction.

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

Conciseness4/5

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

The description is moderately long but well-structured with a clear front-loaded purpose statement and logical flow. Every sentence adds value, although it could be slightly more condensed without losing 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?

Given the tool's complexity (six operations, nested parameters, output schema exists), the description covers all necessary aspects: what operations do, when to use, behavioral traits, parameter semantics, and return structure. It is complete enough for an AI agent to understand and select the tool effectively.

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 coverage is 100%, so the baseline is 3. The description adds extra meaning beyond the schema, such as explaining that 'now' parameter ensures deterministic output by not reading the clock, and clarifying the behavior of exp/nbf deltas in assembleClaims. This provides enough value to raise the score.

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?

The description clearly states the tool's purpose as 'JWT Decode, Validate, Sign and Claim Builder' and lists six specific operations. It explicitly differentiates from the sibling tool encoding_decoding_jwt by noting that this tool also verifies HMAC signatures and builds claims, providing a specific verb+resource with sibling differentiation.

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

Usage Guidelines4/5

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

The description includes explicit guidance on when to use this tool versus the sibling encoding_decoding_jwt, and states limitations for asymmetric algorithms (decoded but not verified/signed server-side). However, it does not provide explicit 'when-not-to-use' or alternatives for asymmetric operations.

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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