repo.open_file

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

With no annotations, the description must fully disclose behavior. It mentions that the tool returns numbered lines and suggests using a range, but it does not detail error handling (e.g., file not found), performance implications, or whether the file is locked. This is insufficient for a read operation with no annotation support.

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 extremely concise, with only two sentences that convey the essential purpose and key guidance. No redundant or unnecessary information.

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 simplicity (3 parameters, no output schema, no annotations), the description covers the basic operation. However, it leaves out return format details beyond 'numbered lines' and does not address edge cases or behavior when parameters are invalid.

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 describes all three parameters with 100% coverage. The description adds marginal value by suggesting the use of start_line and end_line for focused reading, but does not provide additional meaning beyond the schema.

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 verb 'read' and the resource 'source file', and specifies that it reads a line range. However, it does not explicitly differentiate from sibling tools like 'repo.outline' or 'repo.status', though the purpose is clear.

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 advises to specify start_line and end_line for a focused range rather than the entire file, providing some usage context. However, it lacks when-not-to-use guidance or references to alternative tools for similar tasks.

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