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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the underlying endpoint (POST /v1/features.get), which is mildly useful since a read implemented as a POST could otherwise confuse an agent, but it says nothing about not-found behavior or error semantics.

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 action and scope. The endpoint sentence is low-value for an agent but short enough not to be a real cost.

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 single-parameter read tool with no output schema, the essentials are present: what is returned (a feature) and how it is identified. Minor gaps remain around not-found handling and what fields a feature object contains.

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?

There is one required parameter and schema coverage is 100%, so the schema already documents feature_id. The description's "by id" merely restates the parameter without adding format, source, or validation detail — baseline 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?

"Fetch a single feature by id" gives a specific verb (fetch), resource (feature), and cardinality (single), which implicitly contrasts with the sibling autumn_list_features. It does not name that sibling explicitly, but the get/list split is still legible to an agent.

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?

Usage is only implied: "by id" signals that a feature ID must already be known, which suggests listing first, but the description never states when to prefer this over autumn_list_features or what to do if the ID is unknown. No exclusions or prerequisites are given.

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