Pin httpx < 1.0 and simplify beta install docs

[jlowin]

When installing fastmcp with pre-release resolution enabled, pip/uv can pull HTTPX 1.0.dev3, which breaks imports because httpx-sse (a dependency of mcp) uses httpx.TransportError which no longer exists in HTTPX 1.0:

AttributeError: module 'httpx' has no attribute 'TransportError'

This adds an upper bound to keep HTTPX below 1.0 until the ecosystem catches up.

Also simplifies the beta install docs - specifying >=3.0.0b1 in the version allows pip/uv to install the prerelease without needing --pre or --prerelease=allow flags, which avoids pulling prerelease versions of dependencies.

Closes #2973

[coderabbitai]

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Walkthrough

This pull request updates installation documentation across two files by changing package version specifiers from exact pinning format to minimum-version range format. The main installation guide was updated from fastmcp==3.0.0b1 to fastmcp>=3.0.0b1, with corresponding updates to alternative installation methods. The tasks documentation was similarly updated to use >= instead of == for the fastmcp[tasks] dependency specification.

Possibly related PRs

• Prepare docs for v3.0 beta release #2954: Modifies the same documentation files (docs/getting-started/installation.mdx and docs/servers/tasks.mdx) and updates package installation command version specifiers for v3.0 beta.
• Clarify installation for FastMCP 3.0 beta #2953: Updates the same installation documentation files and adjusts install command specifications for FastMCP 3.0.
• Add v3 breaking changes notice to README and docs #2713: Modifies docs/getting-started/installation.mdx and affects package version guidance documentation.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 inconclusive)

Check name	Status	Explanation	Resolution
Description check	❓ Inconclusive	The PR description explains the issue, rationale, and solutions, but the contributors checklist has no checkmarks and appears incomplete.	Complete the contributors checklist by marking completed items and ensuring self-review is confirmed before merging.
Linked Issues check	❓ Inconclusive	The PR addresses the main objective from issue #2973 to add upper-bound constraints to httpx, though the summary doesn't explicitly confirm the pyproject.toml changes.	Verify that pyproject.toml was modified to change httpx from '>=0.28.1' to '>=0.28.1,<1.0' as specified in issue #2973.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The PR title mentions two changes: pinning httpx < 1.0 and simplifying beta install docs, both present in the changeset, but prioritizes the httpx fix as primary.
Out of Scope Changes check	✅ Passed	The documentation updates to installation instructions are complementary to the httpx pinning and directly support the primary objective of simplifying beta install guidance.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[coderabbitai]

Actionable comments posted: 1

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

docs/getting-started/installation.mdx (1)

10-16: Update the beta install note to match the new version range.

The note says to specify the version explicitly, but the command now uses a minimum range. Align the wording so it matches the command.

✏️ Suggested wording

- FastMCP 3.0 is currently in beta. Install by specifying the version explicitly.
+ FastMCP 3.0 is currently in beta. You should install it by specifying the minimum beta version.

[coderabbitai]

⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🌐 Web query:

uv prerelease allow flag behavior version specifiers beta

💡 Result:

Short answer: uv only accepts pre-release versions when you explicitly request them in a version specifier (e.g., >=1.0.0b1 / 2.0.0rc1) or when a package only has pre-release releases. Using --prerelease=allow (or prerelease = "allow" in config) forces the resolver to consider pre-releases for all dependencies (including transitive ones), and uv will prompt you to re-run with --prerelease=allow if resolution fails due to an otherwise-blocked transitive pre-release. [1][2]

Examples / notes:

• Explicit specifier: flask>=2.0.0rc1 will allow that release without other flags. [1][2]
• All-PRs case: if every published version is a pre-release, uv will consider them by default. [1][3]
• --prerelease=allow: opt-in that permits pre-releases globally (useful for alpha/beta installs). [2][4]

Sources: uv docs (pre-release behavior and CLI flag), uv PyPI description. [1][2][3][4]

---

🌐 Web query:

uv add prerelease version constraint >=3.0.0b1

💡 Result:

Use Poetry's allow-prereleases flag and the inequality specifier. For example:

poetry add @">=3.0.0b1" --allow-prereleases

This tells Poetry to accept the prerelease (b1) and any later versions >= 3.0.0b1. Poetry's prerelease handling and the --allow-prereleases option are documented in the dependency spec docs and PEP 440. [1][2]

Sources:
[1] Poetry — Dependency specification (pre-releases / allow-prereleases).
[2] PEP 440 — Handling of pre-releases.

---

Rephrase the label using second person to align with documentation style guidelines, which require second person for instructions and procedures.

The command uv add "fastmcp>=3.0.0b1" is correct without --prerelease=allow. When you explicitly include a prerelease version in the specifier (e.g., >=3.0.0b1), uv accepts it directly without requiring the flag.

Change "Or with uv:" to "You can also use uv:" for consistency with the docs style guide.