CtrlK
BlogDocsLog inGet started
Tessl Logo

api-fuzzing-bug-bounty

Provide comprehensive techniques for testing REST, SOAP, and GraphQL APIs during bug bounty hunting and penetration testing engagements. Covers vulnerability discovery, authentication bypass, IDOR exploitation, and API-specific attack vectors.

60

Quality

70%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

View guide

SecuritybySnyk

Critical

Do not install without reviewing

Fix and improve this skill with Tessl

tessl review fix ./plugins/antigravity-awesome-skills/skills/api-fuzzing-bug-bounty/SKILL.md
SKILL.md
Quality
Evals
Security

Quality

Content

57%Scale 1-3

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

The skill excels at actionability with concrete, executable payloads and techniques across REST, GraphQL, and SOAP APIs. However, it suffers from being a monolithic document that could benefit significantly from splitting into focused sub-files (GraphQL testing, injection payloads, tools reference). The workflow lacks validation checkpoints for confirming vulnerability findings, and some sections explain concepts Claude already understands.

Suggestions

Split the content into sub-files: GRAPHQL.md for GraphQL-specific testing, PAYLOADS.md for injection payloads, and TOOLS.md for the tools reference table, with clear links from the main SKILL.md

Add validation/verification steps to the workflow, such as how to confirm a true positive IDOR vs a false positive, and how to document proof-of-concept findings

Remove the 'API Types Overview' table, 'Purpose' section, 'Inputs/Prerequisites', 'Outputs/Deliverables', and 'When to Use' boilerplate — these add no actionable value and waste tokens

Add a brief step for responsible disclosure or reporting format after vulnerability confirmation to complete the workflow loop

DimensionReasoningScore

Conciseness

The skill is fairly comprehensive but includes some unnecessary elements like the 'API Types Overview' table (Claude knows this), the 'Purpose' section repeating the description, and the 'When to Use' boilerplate at the end. The 'Inputs/Prerequisites' and 'Outputs/Deliverables' sections add little value. However, the core payload/technique content is reasonably dense and useful.

2 / 3

Actionability

The skill provides highly concrete, copy-paste-ready payloads, commands, and test patterns across multiple attack vectors. Examples include specific curl commands, GraphQL queries, SQL injection payloads, IDOR bypass techniques with exact JSON structures, and endpoint bypass patterns. This is immediately executable guidance.

3 / 3

Workflow Clarity

The 5-step workflow provides a reasonable sequence (recon → auth → IDOR → injection → methods), but lacks validation checkpoints and feedback loops. There's no guidance on verifying findings, confirming true positives vs false positives, or documenting results at each step. For security testing involving potentially destructive operations, the absence of verification steps is a notable gap.

2 / 3

Progressive Disclosure

This is a monolithic wall of content (~350+ lines) with no references to external files. The GraphQL section, tools reference table, and detailed injection payloads could all be split into separate reference files. Everything is inline, making it a large single document that consumes significant context window space when loaded.

1 / 3

Total

8

/

12

Passed

Description

82%Scale 1-3

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

This is a strong description with excellent specificity and trigger term coverage for its security testing niche. It clearly lists concrete capabilities and includes natural keywords that security professionals would use. The main weakness is the absence of an explicit 'Use when...' clause, which would help Claude know precisely when to select this skill over others.

Suggestions

Add an explicit 'Use when...' clause, e.g., 'Use when the user asks about API security testing, API pentesting, bug bounty API targets, or exploiting API vulnerabilities.'

DimensionReasoningScore

Specificity

Lists multiple specific concrete actions: testing REST/SOAP/GraphQL APIs, vulnerability discovery, authentication bypass, IDOR exploitation, and API-specific attack vectors. These are concrete, actionable capabilities.

3 / 3

Completeness

Clearly answers 'what does this do' with specific techniques and API types, but lacks an explicit 'Use when...' clause or equivalent trigger guidance. The when is only implied through context (bug bounty, pentesting engagements).

2 / 3

Trigger Term Quality

Includes strong natural keywords users would say: 'REST', 'SOAP', 'GraphQL', 'API', 'bug bounty', 'penetration testing', 'authentication bypass', 'IDOR'. These are terms security professionals naturally use when seeking this type of guidance.

3 / 3

Distinctiveness Conflict Risk

Highly distinctive with a clear niche: API security testing in bug bounty/pentest contexts. The combination of specific API types (REST, SOAP, GraphQL) with specific attack vectors (IDOR, auth bypass) makes it unlikely to conflict with general coding or generic security skills.

3 / 3

Total

11

/

12

Passed

Validation

90%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 10 / 11 Passed

Validation for skill structure

CriteriaDescriptionResult

frontmatter_unknown_keys

Unknown frontmatter key(s) found; consider removing or moving to metadata

Warning

Total

10

/

11

Passed

Repository
popey/claude-code-skills
Reviewed

Table of Contents

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.