build_log

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

Annotations already declare this as a read-only, idempotent, closed-world operation. The description adds useful behavioral context beyond annotations: it decodes UTF-16 logs, reports detected encoding, indicates truncation, and surfaces MATERIAL GUARD warnings from the full log. It does not contradict any annotations.

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 and front-loads the core action. Every sentence adds useful information: the first states the purpose, and the second explains decoding, truncation, and warnings. There is no wasted wording.

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 low-risk annotated read operation and the presence of an output schema, the description covers the key special behaviors an agent needs: UTF-16 decoding, truncation, and MATERIAL GUARD warnings. Minor gaps remain around run_id semantics and explicit selection versus sibling tools, but overall it is sufficiently 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 description coverage is 50%: the lines parameter is documented in the schema, but run_id has no description. The description implies that run_id identifies the build run whose log is tailed, but it does not document format or acquisition. This is adequate but leaves a clear gap.

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 states a specific verb and resource: "Tail a build run's log." It clearly identifies the operation and the special UTF-16 decoding behavior. However, it does not explicitly differentiate itself from the closely related sibling build_status, so it falls short of 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?

The description does not say when to use build_log versus alternatives such as build_status or build_wait. The parenthetical "see build_status" points to another tool but does not establish selection criteria. Usage is only implicit from the tool name and purpose.

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