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

With no annotations, the description carries the full burden. It adds meaningful context by scoping the selection 'for this authorization' and describing it as setting a 'current' state, hinting at session-scoped persistence. It says nothing about overwriting a prior selection, validation failures, or permissions, so it is only partially adequate for a stateful mutation.

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?

One sentence, front-loaded with the verb and the outcome, with no filler. It is appropriately sized, though it has room to add one clause of behavioral detail without becoming bloated.

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 one-parameter stateful tool with no annotations and no output schema, the description covers purpose and scope but omits behavior on repeat calls, failure modes, and whether any confirmation is returned. Adequate as a minimum viable definition but with clear 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 coverage is 100% for the single site_id parameter, so the schema already carries the semantics and the baseline is 3. The description restates that the site comes from list_sites, which duplicates rather than extends the schema's own 'Numeric site id from list_sites'.

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 action ('Remember a site ... as the current site'), naming the resource and the resulting state, which separates it from create_site (creates) and list_sites (enumerates). It does not explicitly name those siblings, so it falls short of the 5 bar.

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 reference to list_sites implies the intended workflow (pick an id from that tool, then select it), which is useful implied guidance. However, it never states when this should be called versus other tools, whether a site must already be selected, or what happens if it is called twice.

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