get_frontmatter_field

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

No annotations are present, so the description carries the full burden. It discloses key behaviors: type preservation of the return value and propagation of upstream 4xx errors. It doesn't mention auth or rate limits, but those are likely less relevant for a simple getter; the provided disclaimers are valuable.

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 two sentences, front-loaded with the core action, and every phrase earns its place. It efficiently conveys the return type, error behavior, and a sibling alternative without redundancy.

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 simple read tool with well-described parameters and no output schema, the description covers the essential context: what is returned, type preservation, error handling, and an alternative for broader reads. The tool is simple enough that this is complete.

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 100% with descriptions for all parameters (filepath, field, vaultId). The description adds no parameter-level semantics beyond what the schema already provides, so 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?

The description uses a specific verb ('Returns') and identifies the resource ('named frontmatter field's value') with added detail about type preservation. It also distinguishes itself from sibling get_file_contents by noting that tool reads all fields at once.

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 clearly implies when to use this tool (reading a single field) and explicitly recommends an alternative for reading all fields. It does not explicitly say 'use this when you need one field' but the guidance is clear enough to steer the agent.

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