Nanostores MCP

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

Annotations already declare readOnlyHint=true and idempotentHint=true, indicating safe, repeatable read operations. The description adds valuable context beyond this by specifying the return content ('recent events, change frequency, action calls, and errors'), debugging use cases, and optional storeName behavior, though it doesn't mention rate limits or auth needs, which keeps it from a perfect score.

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 front-loaded with the core purpose, followed by usage guidance and examples, all in three concise sentences with zero wasted words. Each sentence adds specific value, making it efficient and well-structured for quick comprehension.

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?

Given the tool's debugging complexity, rich annotations (readOnlyHint, idempotentHint), 100% schema coverage, and the presence of an output schema, the description is complete enough. It covers purpose, usage, behavioral context, and examples, leaving no critical gaps for an agent to invoke the tool effectively.

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 description coverage is 100%, so the schema fully documents all 6 parameters. The description adds minimal parameter semantics beyond the schema, such as implying storeName's optionality and providing example usage, but doesn't explain parameter interactions or deeper meanings, aligning with the baseline for high schema coverage.

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 clearly states the tool's purpose with specific verbs ('debugging a specific store's runtime behavior') and resources ('store runtime activity'), distinguishing it from siblings like nanostores_find_noisy_stores or nanostores_store_summary by focusing on detailed event-level debugging rather than high-level summaries or noise detection.

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 explicit guidance on when to use this tool ('when debugging a specific store's runtime behavior — why it updates too often, what actions trigger changes, or whether it emits errors'), includes an alternative usage pattern ('Omit storeName to get activity across all stores'), and offers concrete examples, making it clear how to apply it in different scenarios.

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