guest_read_file

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety bar is low. The description still adds substantive behavior: output is base64 with a SHA-256 digest, plus hard size ceilings (64 KiB default, 8 MiB maximum) and a context-budget warning that no annotation conveys.

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?

Three sentences, front-loaded with what the tool does and the output format, followed by limits and then the large-file caveat. No filler or restatement of the name.

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?

An output schema exists, so return structure needn't be spelled out, and the size/encoding behavior is covered. The remaining gap is parameter-level clarity for vm_name and the named max_bytes parameter, minor for a 3-parameter tool.

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 carries the burden. It partially compensates by specifying that guest_path must be absolute and by documenting the byte limits that map to max_bytes (default 64 KiB, max 8 MiB), but it never names max_bytes or explains vm_name, leaving the mapping implicit.

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?

States a specific verb+resource (read an absolute guest file path) and the return encoding (base64 plus SHA-256), which an agent can immediately distinguish from guest_write_file. It does not explicitly name or exclude any sibling, which keeps it from a 5.

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 gives one real usage rule — for large files, use bounded chunks rather than inflating model context — which is genuinely actionable. But 'the lab APIs' is vague; the concrete siblings lab_stage/lab_collect are never named, so the agent must guess which route to take.

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