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

The description discloses behavioral traits beyond the annotations: handling of SKILL.md, text vs binary files, size limits resulting in error field, and the need for view access. The annotations already indicate read-only (readOnlyHint=true), so the description adds valuable context.

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 concise with no unnecessary words, but the file-type handling information could be better structured with bullet points. It is front-loaded with the main purpose and quickly dives into details.

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 presence of an output schema, the description adequately covers all behavioral aspects: path matching, version pinning, file type handling, auth requirements. No gaps remain for an agent to invoke the tool correctly.

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 100%, so baseline is 3. The description adds the 'manifest matching' context for path, which is marginally beyond schema. It does not repeat existing parameter descriptions, which is appropriate.

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 'fetch', the resource 'single file from a skill version's file tree', and the method 'by path'. It distinguishes this tool from siblings like get_skill (which returns the manifest) and get_skill_files (which likely lists files).

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 explains that path must exactly match a manifest entry, suggests using get_skill to inspect the manifest, and specifies how different file types are handled. It also mentions the required view access. However, it does not explicitly contrast with get_skill_files or state when not to use this tool.

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