Introduction

Assembly attributes are metadata applied at the assembly level in .NET. They can describe version information, product identity, COM visibility, internals exposure, and other configuration details, so the main best practice is to treat them as part of your build contract rather than as random decoration.

Keep Identity and Versioning Intentional

A few assembly attributes show up repeatedly because they affect packaging and diagnostics.

1using System.Reflection;
2
3[assembly: AssemblyTitle("MyProduct")]
4[assembly: AssemblyDescription("Background worker for billing")]
5[assembly: AssemblyCompany("Example Co")]
6[assembly: AssemblyProduct("Billing Suite")]
7[assembly: AssemblyVersion("1.0.0.0")]
8[assembly: AssemblyFileVersion("1.0.0.0")]

The important point is not to fill these out mechanically. Decide what each version number means in your build and release process.

In modern SDK-style projects, many of these values are often generated from the project file, so duplicating them manually can create confusion.

Prefer Project-Level Configuration in Modern .NET Projects

In older .NET projects, AssemblyInfo.cs was the normal place for assembly attributes. In SDK-style projects, many common attributes are generated from the .csproj file.

1<PropertyGroup>
2  <TargetFramework>net8.0</TargetFramework>
3  <AssemblyName>MyProduct</AssemblyName>
4  <Version>1.2.3</Version>
5  <Company>Example Co</Company>
6  <Product>Billing Suite</Product>
7</PropertyGroup>

That keeps build metadata centralized. If you also define the same attributes manually in source, you can end up with duplicate-attribute build errors or unclear ownership of the metadata.

Use Specialized Attributes Sparingly and Deliberately

Some assembly attributes have stronger behavioral consequences.

Examples include:

• 'ComVisible'
• 'CLSCompliant'
• 'InternalsVisibleTo'
• 'AssemblyMetadata'

using System.Runtime.CompilerServices;

[assembly: InternalsVisibleTo("MyProduct.Tests")]

Attributes like InternalsVisibleTo are useful, but they should have a clear purpose. If many assemblies are granted access to internals casually, encapsulation erodes quickly.

Separate Build Identity from Runtime Configuration

Assembly attributes are best for metadata that should travel with the built binary. They are a poor place for values that vary by environment, tenant, or deployment slot.

A good rule is:

• version and product identity belong here
• custom metadata may belong here if tools read it
• database endpoints, API URLs, or feature flags do not belong here

That boundary keeps assembly metadata stable and makes runtime configuration easier to manage through normal configuration systems.

Do Not Treat Assembly Attributes as a Dumping Ground

Assembly metadata should be stable and meaningful. If a value changes every time a developer experiments locally, it probably does not belong in assembly-level metadata.

A good rule is:

• identity metadata belongs here
• release metadata may belong here if the build pipeline owns it
• environment-specific runtime settings usually do not belong here

That separation keeps assembly metadata useful for diagnostics and tooling.

Make the Build Own Repetitive Values

If version numbers, informational version strings, or source revision markers are part of release management, let the build pipeline stamp them consistently.

That reduces manual edits and prevents mismatches between what the assembly says and what the package or deployment system says.

In other words, assembly attributes are best when they are boring, predictable, and accurate.

Common Pitfalls

• Defining common assembly attributes both in AssemblyInfo.cs and in the project file.
• Using assembly metadata without a clear versioning policy behind it.
• Overusing InternalsVisibleTo and weakening assembly boundaries.
• Putting environment-specific configuration into assembly attributes.
• Forgetting that modern SDK-style .NET projects often auto-generate many standard attributes.

Summary

• Treat assembly attributes as part of the build and packaging contract.
• In modern .NET projects, prefer project-file ownership for common metadata.
• Keep version numbers intentional and consistent with release policy.
• Use stronger behavioral attributes such as InternalsVisibleTo sparingly.
• Good assembly metadata is stable, centralized, and purposeful.