guard_budget

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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint=false and destructiveHint=false, so the safety profile is covered. The description adds two genuine behavioral details beyond that: the tokens are an estimate computed as chars/4, and only the top-5 tools are reported (an explicit truncation rule). It does not say whether counts are cumulative for the session or since the last call, which is the main remaining gap.

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?

It is short and front-loaded with no filler, but it is written as a compressed noun phrase rather than a sentence, with no verb and no leading statement of what the tool returns. Brevity here shades into under-specification rather than efficiency.

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?

An output schema exists, so return values need not be explained, and with no parameters the surface area is small. Still, for a session-scoped metrics tool the description omits whether measurements are cumulative, per-session or reset, and how it relates to the sibling status tools, so it is only minimally complete.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate and the baseline of 4 applies. The description correctly introduces no argument concepts.

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 names the resource loosely ('Session tool-output') and lists three reported metrics (chars, estimated tokens at chars/4, top-5 tools), so an agent can infer this is a stats/introspection tool. However, there is no verb and no differentiation from siblings such as guard_status, which likely also reports session state, leaving the exact purpose ambiguous.

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?

There is no guidance on when to call this versus guard_status or the other guard_* introspection tools, and no stated trigger such as 'call when you need to check context budget usage'. The agent must infer usage entirely from the fragmentary noun phrase.

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