local_explain

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

With no annotations, the description carries the full behavioral burden and does so well: it discloses the read-only/no-write-tools guarantee, the ESCALATE outcome for vague questions, the output shape (dense answer with path:line citations, never file dumps), and the tier/answer_budget trade-off. These are traits an agent could not infer from the schema.

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?

Front-loaded with a clear Args/Returns structure, and every subsection earns its place. The opening sentence is somewhat long and the quoted example questions add length, but no content is filler.

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 four-parameter read tool with no annotations, the definition is complete: purpose, routing against alternatives, mode selection, budget control, and the escalation/failure mode are all covered. The return-value note is brief and appropriate given an output schema exists.

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 0%, so the description must compensate, and it documents all four parameters: workspace_root (absolute repo root), question (must be specific or it ESCALATEs), tier ('fast' default, 'deep' for multi-file reasoning), and answer_budget (soft character cap, keep small). Each adds meaning beyond the bare schema titles.

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 gives a precise verb+resource: 'Ask the local model to read the repository and answer a FACTUAL question about it,' with concrete sample questions. It also implicitly separates itself from the write-oriented sibling local_edit via 'Read-only: the local model has no write tools.' It stops short of naming its actual siblings (local_verify, local_status), so differentiation from those is left to inference.

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 explicitly states when to use it ('USE THIS INSTEAD OF Read/Grep when you need to know what is in files but do not need the files themselves in context') and names the condition that selects the alternative (when you do need the files in context). Both the positive trigger and the exclusions are spelled out.

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