canvas_clear_cache

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

Annotations already declare the safety profile (readOnlyHint=true, destructiveHint=false), so the description's real contribution is the disclosure that this touches only local navigation cache and performs no upstream Canvas writes. It further characterizes the cache with a 90-second TTL, a 128-entry/8 MiB bound, and invalidation on credential replacement — concrete behavior not present in any structured field.

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 action and its scope, then the two facts that most affect a decision to call it (TTL and bounds). No filler, no restating of the tool name, no redundant safety boilerplate.

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 zero-parameter tool with an output schema and full annotation coverage, this covers scope, safety boundary, and cache lifecycle well. The one gap is that it does not state the effect on in-flight or subsequent navigation calls (i.e., that the next call repopulates the cache), though the output schema carries return details.

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 no parameter meaning to convey; the baseline for a no-argument tool applies. The description correctly avoids inventing scope or filter options that the empty schema does not support.

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 with an explicit scope: "Clear this account's navigation cache." The scope qualifier ("this account's") and the note that it makes no upstream Canvas writes make it unmistakable against every sibling in the list, none of which touch local cache state.

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 explicit when-to-use clause and no named alternative, but the stated 90-second default TTL implicitly tells the agent that manual clearing is usually unnecessary and that waiting is a valid substitute. "Credential replacement creates a fresh cache" gives a second implicit condition under which calling this is redundant.

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