MCP Spine

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

No annotations are provided, so the description carries the full burden. It discloses the tool's read-only nature by stating it 'recalls' cached results without mentioning mutations, but lacks details on cache behavior (e.g., expiration, scope), error handling, or response format. It adds some context but is incomplete for behavioral transparency.

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 in the first sentence, followed by usage guidance. Both sentences earn their place by adding value, with zero wasted words, making it highly efficient and well-structured.

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 moderate complexity (3 parameters, no output schema, no annotations), the description is reasonably complete. It clarifies the tool's purpose and usage but lacks details on output format or cache mechanics. With no output schema, more guidance on return values would improve completeness, but it's adequate for a recall operation.

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 the three optional parameters. The description adds no parameter-specific information beyond what the schema provides, such as how 'query' matches keywords or how 'last_n' interacts with other filters. Baseline 3 is appropriate as the schema does the heavy lifting.

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 specific action ('Recall cached results from previous tool calls') and resource ('cached results'), distinguishing it from its sibling 'spine_set_context' which likely sets rather than retrieves context. It avoids tautology by explaining functionality beyond the 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?

It provides explicit guidance on when to use this tool ('to check what a tool returned earlier without re-calling it') and a specific scenario ('especially if that tool is no longer in your active tool set'), which helps differentiate it from alternatives like re-invoking tools directly.

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