Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Given the readOnlyHint annotation, the description adds valuable behavior beyond annotations: it discloses that content is returned as a string and that binary content is base64-encoded. This addresses the return format, which is not itemized in the schema. It does not discuss auth requirements or error behavior, but for a simple read operation the additional context is sufficient.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise at three sentences, with the primary verb and resource in the first sentence. It front-loads the core purpose and then provides two clarifying details (templated URI handling and binary encoding) without redundancy or tangential fluff.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple single-parameter tool, the description covers the key usage nuances (URI types) and return format (string/base64). An output schema exists to detail structured return values, so the description does not need to repeat that. It is complete for an agent to correctly invoke the tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema description for 'uri' is brief ('The URI of the resource to read'), but the tool description adds meaningful semantics by explaining how URIs work for static vs. templated resources. This helps the agent correctly construct the parameter value, which is valuable beyond the schema's minimal definition.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states 'Read a resource by its URI' with a specific verb and resource, clearly distinguishing this from sibling tools like list_resources (enumeration vs. reading a specific resource). It also distinguishes between static and templated URIs, adding precision.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides clear context on how to use the tool—by giving exact URIs for static resources and filled-in parameters for templated ones—making the usage pattern explicit. However, it does not explicitly mention when not to use this tool or direct users to alternatives like list_resources for enumeration, so it falls short of a full 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.