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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description's 'Get' aligns with these. The description adds no new behavioral context such as error behavior, ownership semantics, or return format. No contradiction exists.

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 a single six-word sentence, front-loaded with the verb and object, and contains no filler or redundant detail. It is an ideal length for this simple retrieval operation.

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 single-parameter, read-only get-by-ID tool with rich annotations, the description is nearly complete. It could mention what the response contains or explicitly point to list_subscriptions for enumeration, but the current text is sufficient for an agent to invoke the tool correctly.

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 input schema already provides full documentation for subscriptionId with a clear description and UUID format, and the description just restates 'by ID' without adding further semantics. Since schema description coverage is 100%, the baseline of 3 is appropriate.

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?

Description uses the specific verb 'Get' and identifies the resource as 'a market signal subscription by ID', clearly distinguishing it from sibling list_subscriptions and other market signal operations. The scope is unambiguous and aligns with the tool name.

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 phrase 'by ID' implies the tool should be used when the caller already has the subscription ID, but there is no explicit guidance about alternatives such as list_subscriptions for discovering subscriptions or when not to use this tool. Usage context is present but only implicit.

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