Get a source fragment

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

With no annotations, the description carries the full burden. It discloses that the tool returns full text and source position, which is useful, but it does not mention error handling (e.g., invalid id), potential empty results, or any permission requirements. For a read-only fetch, this is adequate but not rich.

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 long, front-loaded with the core function, and adds value with the sibling differentiation. There is no redundant or filler text.

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 one-parameter fetch tool without an output schema, the description adequately covers purpose, return content, and usage context relative to siblings. It could optionally describe the exact response structure, but that is not essential given the tool's simplicity.

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 provides 100% coverage for the single 'id' parameter, including an example. The description reinforces the parameter's role ('by id') but does not add further semantic details 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 clearly states a specific action ('Fetch one fragment by id') on a specific resource ('a source fragment') and adds what is returned (full text and location). It also distinguishes the tool from siblings by noting that other tools cite fragment ids and this is how to open one.

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 implies when to use the tool: when you have a fragment id and need to view its content or context. The phrase 'Every other tool cites fragment ids; this is how you open one' provides clear usage context, though it does not name a specific alternative or explicit 'when not to use' scenario.

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