Read a resource by its URI.
For static resources, provide the exact URI. For templated resources, provide the URI with template parameters filled in.
Returns the resource content as a string. Binary content is base64-encoded.
| Name | Required | Description | Default |
|---|---|---|---|
| uri | Yes | The URI of the resource to read |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
Output schema / descriptionAdded value: +"Generic wrapper for non-object return types."Output schema / descriptionRemoved value: -"Generic wrapper for non-object return types."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnly, idempotent, non-destructive). The description adds valuable behavioral details: it clarifies return type (string) and base64 encoding for binary content, and explains templated resource handling. This exceeds annotation coverage and provides useful context without contradiction.
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 three sentences, front-loaded with the core purpose. Each sentence earns its place: purpose, usage variation, and return format. No fluff or redundancy. Structure is clear and scannable.
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?
The description covers the main usage scenarios (static and templated), return format, and binary handling. While it doesn't mention error handling or edge cases, for a generic read tool with an output schema and comprehensive annotations, it is adequately complete. The lack of sibling differentiation is a minor gap but not critical for the tool's own functionality.
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 minimal ('The URI of the resource to read'), but the tool description significantly enriches meaning by explaining static vs templated URIs and the need to fill template parameters. This adds substantial semantic value beyond the schema, compensating for the schema's brevity.
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 a clear verb and resource: 'Read a resource by its URI.' It precisely defines the action without ambiguity, and it differentiates itself from specialized siblings by being the generic resource reader, though it doesn't explicitly name alternatives. The purpose is immediately understandable.
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 gives instructions on how to provide the URI (static vs templated) but does not provide any guidance on when to use this tool versus the many specialized siblings (e.g., judgment_get_header, legislation_get_section). An agent cannot infer when to choose read_resource over a domain-specific reader, which is a significant gap.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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