[SakarPaisen]

What

Closes #3.

hash_text takes an optional uppercase: bool = False. The digest is computed once; only the hexadecimal string is reformatted, so the algorithm name, the default lowercase output and the error handling are unchanged.

>>> hash_text("abc")["digest"][:8]
'ba7816bf'
>>> hash_text("abc", uppercase=True)["digest"][:8]
'BA7816BF'

Scope

• src/mcp_tools_lab/tools/hashing.py — the new optional parameter and docstring.
• tests/test_hashing.py — four new tests (default unchanged, documented example, all three algorithms, empty text).
• docs/tool-guide.md — the signature and one example.

server.py registers hash_text directly, so the typed parameter is exposed to MCP clients without another wrapper.

Tests added

• test_uppercase_digest: hash_text("abc", uppercase=True) equals the uppercase of the known SHA-256 vector, and algorithm stays sha256.
• test_uppercase_is_optional_and_algorithm_is_unchanged: the default still starts with ba7816bf, and uppercase=False equals the plain call.
• test_uppercase_supports_every_algorithm: sha256, sha512, blake2b — uppercase equals the lowercased digest uppercased, same length, algorithm unchanged.
• test_uppercase_empty_text: empty input hashes to E3B0C442…B855 in uppercase.

Checks

• python -m pytest tests/test_hashing.py -q — 11 passed
• python -m pytest -q — 68 passed
• python .github/scripts/check_rules.py — Scanned 11 files under src/ for print() and network imports: OK
• Direct call check printing both results to confirm the exact digests

Python: 3.13 on Windows 11.

(Full disclosure: I used an AI coding assistant for this change, and I reviewed and verified everything submitted here.)