mcp-synology

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

Annotations already declare readOnlyHint=true. Description adds valuable behavioral context: it discloses recursive traversal ('including all files and subdirectories') and enumerates return values ('total size, file count, and directory count') not visible in annotations. Does not mention performance characteristics or permission requirements, but adequately supplements annotations.

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?

Three sentences with zero waste: sentence 1 defines action and scope, sentence 2 specifies return values, sentence 3 provides usage guidance. Logical front-loaded structure where every sentence earns its place.

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?

Appropriate for a single-parameter tool with output schema present. Description covers the operation, recursive behavior, and return value summary without needing to duplicate full output schema documentation. Annotations cover safety profile. No gaps requiring elaboration.

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?

Schema coverage is 0% (path parameter has title/type but no description), so description must compensate. It minimally compensates by implying the input is a directory path ('Calculate... of a directory'), but does not explicitly document the path parameter semantics, expected format, or examples. This meets the minimum viable threshold given the single parameter and clear tool name.

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?

Clear specific verb ('Calculate') with resource ('total size of a directory') and scope ('including all files and subdirectories'). The phrase 'best tool for answering how much space does X use' effectively distinguishes from siblings like get_file_info (single file) and list_files (enumeration without size aggregation).

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?

Explicitly states when to use ('best tool for answering how much space does X use questions'), providing clear contextual guidance. However, lacks explicit 'when not to use' or named alternatives (e.g., does not mention to use get_file_info instead for single files).

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