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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds non-obvious behavioral context beyond that: authentication is via a locally generated secret in the X-Context-Key HTTP header and must never be passed as a tool argument, which is exactly the kind of invocation detail an agent cannot get from the schema.

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?

Three short sentences, front-loaded with the purpose, then the access condition, then the credential placement rule. Nothing is repeated and every sentence earns its place.

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?

Auth mechanism and the empty-argument contract are covered, but with no output schema the description never hints at what the 'limits' actually contain or their format, leaving a gap for a read tool.

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?

This tool takes zero parameters, so the baseline is 4. The description reinforces this by noting the credential belongs in an HTTP header rather than in arguments, clarifying why the schema is empty.

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: read guest context limits. However, it does not differentiate itself from sibling 'read_guest_context' (or the save/delete guest context variants), so an agent must infer the distinction from the name alone.

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?

'No agent registration needed' gives one implicit condition under which this tool applies, which is useful for a guest/anonymous caller. But there is no explicit when-to-use guidance relative to read_guest_context, nor any when-not-to-use statement.

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