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

Annotations already declare readOnlyHint/destructiveHint=false, but the description adds real behavioral context beyond them: the payload travels as base64 text through the conversation and costs 'roughly a third more than the file itself,' there is a size ceiling, and reading requires only page-visibility permission. These are the operational traits an agent needs before calling.

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 what is returned and how the target is identified, then the copy workflow, then the size/permission caveats. Dense and purposeful, though the pm-files redirect could be trimmed to a single clause without losing meaning.

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 carries the return value itself (base64 bytes) and bounds it with a size ceiling and the alternative path for large files. Nothing needed to invoke it correctly — target resolution, permission requirement, output form, limits — is missing.

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 the baseline is 3; the description still adds value by tying 'filename' to get_wiki_page's listing and framing pageId vs spaceKey+title as mutually exclusive page-identification routes, which the schema alone presents only as optional fields.

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 and resource — 'Read one file attached to a wiki page — its bytes, base64-encoded' — and spells out both addressing schemes (pageId, or spaceKey + title, plus filename). This clearly separates it from get_wiki_page (whole page), get_attachment (non-wiki), and add_wiki_attachment (the write counterpart).

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?

Explicitly names the workflow it belongs to — 'read it here, write it with add_wiki_attachment' — and names the alternative when it doesn't apply: 'for anything larger — or for putting the file on disk — the pm-files MCP server saves it to a path instead (local_files_setup says how to connect it).' Both the use case and the exclusion are stated.

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