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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the safety profile is covered. The description adds genuine behavioral detail beyond that: the 1-based numbering matches the order the group displays links in, which is the key fact an agent needs. It omits ordering stability and what happens with zero links, keeping it below a 5.

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 first two sentences restate each other almost verbatim ('links ... numbered as the group shows them' / 'links ... under the description, numbered from 1'). The valuable routing sentence is buried last instead of front-loaded, so the definition wastes roughly a third of its length.

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 full annotation coverage and no output schema, the description conveys the return shape (an ordered, 1-based list of sidebar links) and how the result feeds other tools. Only pagination/empty-list behavior is unstated, which is minor here.

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?

Only one parameter and schema coverage is 100%, with the schema itself explaining the URL-name format. The description adds no syntax or edge-case detail about the 'group' argument beyond 'a group's sidebar', so the baseline 3 applies.

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 ('lists the links the group shows in its sidebar') plus the distinguishing trait that they are numbered. That separates it from add_group_link, but it never explicitly says it is the read counterpart of update_group_link/delete_group_link — the relationship is only implied by the trailing sentence.

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 final sentence 'update_group_link and delete_group_link take the number' gives a concrete reason to call this tool: to obtain identifiers before mutating. It stops short of explicit when-not guidance or naming a search alternative, but the context is clear enough to act on.

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