Skills/PyPI/mcp-yahoo-fantasy

mcp-yahoo-fantasy@0.1.0

VERIFIED· not started

Publisher claims: "An MCP server for Yahoo Fantasy Sports (read + write)." Observed in sandbox: no network, touches nothing outside the project, writes no memory.

Registry PyPI (MCP server)Publisher michaelfromorg · publishing for 159 daysInstalls 28Last detonated 4d ago
$claude mcp add mcp-yahoo-fantasy -- uvx mcp-yahoo-fantasy
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Coverage

Not started: dependency install failed; the server itself was not observed.
Tested
the dependency install step · every file read, file written and host contacted by what ran
Not tested
server startup · the tool list · tool behavior

What this means for the label: Verified here covers what ran. The server's tools were not exercised with a real credential, so nothing about their behavior is asserted; the credential summary below says what to do with that.

Before you give it your token

It will ask for
YAHOO_ACCESS_TOKENYAHOO_CONSUMER_SECRETYAHOO_OAUTH_FILEYAHOO_REFRESH_TOKEN or --client-secretConfiguration, not credentials: YAHOO_CONSUMER_KEY, YAHOO_ENV_FILE, YAHOO_LEAGUE_KEY, YAHOO_MCP_CONFIG_DIR
Where it talks to
no vendor host named in the codeAlso yahoo.com — not the publisher's domain; check what for before connecting.
What the honeypot saw
no credential files read · no network
What we could not test
server startup · the tool list · tool behavior

Connect it with a scoped credential, under the guard, and read the third-party hosts first. The code names yahoo.com as well as its own vendor. The guard injects YAHOO_ACCESS_TOKEN, YAHOO_CONSUMER_SECRET, YAHOO_OAUTH_FILE, YAHOO_REFRESH_TOKEN only into requests to the host you bind (and its subdomains) and refuses the rest.

$vet-skills run --net declared -- uvx mcp-yahoo-fantasy

Never paste a credential into a chat, a ticket or a report, including ours. How the guard holds it.

Is [email protected] safe to install?

KillerSkills ran it in the KillerSkills honeypot sandbox (2 scenarios; not started: dependency install failed; the server itself was not observed) on 2026-11-10 and scored it 86/100 (Verified). In what ran, nothing we could detect went wrong: no undeclared network egress, no credential reads, no persistent instruction writes. What it does with a real credential was not observed; the static findings and the publisher carry the rest of the score. Summary: no network, touches nothing outside the project, writes no memory.

Behavior trace

Honeypot run · 0 s · 2 scenarios · 0 deviations
t+CategoryObserved action
0.0sprocessno install scripts in bundle
0.1sprocessdependency install exit 1 ·
0.1sclaimednot started: dependency install failed (exit 1); the server itself was not observed
0.1sprocessscript backend runs setup only
0.1sprocessno install scripts to re-run

Static findings

HIGH
Access to sensitive file pathssrc/yahoo/login.py:60 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files# The server rebuilds oauth2.json from .env on startup, so a fresh login just works.Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/auth.py:5 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesthe credentials (client id/secret + refresh token) to a `.env` file. `.env` is the source ofFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/login.py:12 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesback to $YAHOO_CONSUMER_KEY/$YAHOO_CONSUMER_SECRET, then to whatever is already in `.env`,Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/auth.py:10 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesalways takes effect. With no `.env`/env credentials, an existing `oauth2.json` (e.g. one youFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/login.py:5 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filestokens) and saves the resulting credentials to `.env`, which the server loads on startup.Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/auth.py:9 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files`yahoo_oauth` reads and refreshes; rebuilding it from `.env` each start means a fresh loginFix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/auth.py:29 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system filesENV_FILE = Path(os.environ.get("YAHOO_ENV_FILE", Path.cwd() / ".env"))Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05
HIGH
Access to sensitive file pathssrc/yahoo/login.py:48 · Access to sensitive file paths — SSH keys, AWS credentials, env files, or system files# secrets.json -- we persist to .env instead.Fix: Stop enumerating or reading credential locations; take secrets from a declared environment variable the user sets on purpose.
AST05

Cost to the agent

Instructions loaded
≈52 tok
1 file · 11 in bundle
Tool list per prompt
≈0 tok
0 tools · 0 per tool
Handshake
no reply
launch to tools/list, stdio
Undocumented tools
0
description under 20 chars · avg 0

Tokens estimated at four characters each. The tool list is re-read by the agent on every turn, so it is the number to compare between servers that do the same job: ranked across the index.

Known vulnerabilities

No advisories in OSV for mcp-yahoo-fantasy@0.1.0 as of 4d ago. This is the package itself, not its dependencies.