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

Beyond the readOnlyHint and openWorldHint annotations, the description discloses that the post is public, that the response includes engagement counts and media, and that the call costs 1 credit. It does not cover error behavior or rate limits, but it adds meaningful behavioral context for a read-only retrieval tool.

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 short and front-loads the key facts about what a post contains and the credit cost. The opening 'Post.' largely restates the tool name and title, so it is not perfectly economical.

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?

For a simple two-parameter retrieval tool with read-only/open-world annotations, the description covers purpose, public visibility, returned fields, and cost. The main gap is the undocumented cache_max_age parameter and lack of return-format detail, though no output schema exists.

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?

The description mentions neither the required url parameter nor cache_max_age. The schema documents url with an example, but cache_max_age has no schema description, so the description fails to compensate for the 50% schema description coverage.

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 identifies the resource as a single public Mastodon post and lists the data it includes: favourite, reply and boost counts plus attached media. It stops short of explicitly distinguishing this from siblings such as mastodon_postReplies or mastodon_userPosts, which keeps it from 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 gives no guidance on when to use this tool versus alternatives like mastodon_userPosts, mastodon_postReplies, or mastodon_profile. It also provides no exclusions or prerequisites beyond the implicit need for a post URL.

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