Read your instance's local timeline

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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint false). The description adds behavioral context beyond those: content is public, scoped to the local instance, and can be a high-volume 'firehose' on large instances, which is useful for expecting large result sets.

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 only two sentences and front-loads the core definition. The second sentence adds useful usage context, though the subjective 'most useful timeline there is' is slightly less precise than a more objective condition would be.

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 read-only timeline tool with robust annotations and fully documented parameters, the description plus input schema is sufficient. It establishes scope, content type, and scale. It doesn't explicitly describe the response shape, but the name and schema's pagination references make the return type reasonably clear.

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 100%, so every parameter already has a meaningful description. The tool description adds no additional parameter-level semantics, so the baseline score of 3 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 defines the resource and scope: 'Everything public posted by accounts on your own instance.' This distinguishes it from the federated timeline (other instances) and the home timeline (followed accounts), while the tool name and title provide the read/get verb.

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 useful context ('On a small themed instance this is the most useful timeline there is; on mastodon.social it is a firehose') that implies when it is appropriate, but it does not explicitly name alternatives like get_federated_timeline or get_home_timeline or state when not to use it.

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