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

Annotations already declare this a non-destructive read operation, so the safety bar is low. The description adds real behavioral context beyond them: .gitignore is respected, results are capped at 1000 files, and output is one 'path (size)' line per entry. It does not say whether the 1000-file cap truncates silently or how results are ordered, which is the main remaining gap.

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?

Two compact sentences with no filler: purpose and output format come first, then the optional narrowing parameter with examples. Every clause carries information an agent would otherwise have to guess.

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?

With no output schema, the description usefully specifies the return format and the file-count ceiling, so an agent can plan around result size. It is nearly complete for a two-parameter read tool; only ordering and truncation behavior are unspecified.

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 coverage is only 50%: projectId is documented in-schema, but glob carries no description there. The description compensates well by giving concrete glob syntax examples ('src/**/*.tsx', 'public/**/*.{png,jpg}'), which is meaning the schema does not provide. It does not explain whether glob is relative to project root or how invalid patterns behave, keeping it below a 5.

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 opens with a specific verb and resource: 'Lists project files with their sizes.' It also specifies the exact rendering format, so the agent knows precisely what it gets back. It stops short of naming the closest sibling (search_files) or contrasting with read_file, so sibling differentiation is left implicit.

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?

Usage is only implied: a glob filter suggests use for narrowing listings, but the description never states when to choose this over search_files or read_file. No exclusions, prerequisites, or alternative-routing guidance are given, leaving the agent to infer the browsing-vs-searching split.

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