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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds genuinely useful behavior beyond that: text returns inline, binary returns as base64 below an inline size limit. It stops short of saying what happens at or above that limit (error, truncation, or a link), which is the main behavioral question an agent would have.

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 short sentences, front-loaded with the core action and followed by return-format behavior. Nothing is wasted, though "as base64 blob" is slightly loose phrasing for what is presumably a base64-encoded string.

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 does carry some of the return-shape burden by explaining inline vs base64 representations, which is appropriate. However, for a 2-parameter content-fetch tool with zero schema coverage, missing details on the hash parameter and the oversize-limit outcome leave real gaps.

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 must carry the parameter burden and it largely does not. "Inline size limit" gestures at max_bytes but never explains it, its units beyond the schema's integer type, or the 25 MB maximum, and file_hash is not explained at all (what hash format or where to obtain it).

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?

"Read a visible Files.fm file" gives a specific verb plus resource, and the second sentence clarifies that reading means fetching content rather than metadata. It does not explicitly distinguish itself from siblings like filesfm_get_file_info or filesfm_get_doc, so an agent must infer which one returns content.

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?

There is no explicit when-to-use guidance and no named alternative. The word "visible" hints at an access prerequisite, but the description never says when to prefer this over filesfm_get_file_info (metadata) or filesfm_get_doc, nor what to do if the file is not visible.

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