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

Annotations already declare this a safe read (readOnlyHint=true, destructiveHint=false), so the bar is lower. The description adds real operational context the annotations cannot: it is 'the heaviest read in HookSend', should be called once and cached, and it surfaces webhook/access-token state, which is flagged as the usual cause of failed sending.

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 metric inventory is long but front-loaded and earns its place by defining return scope in the absence of an output schema. The usage and caching guidance is packed into the final two sentences with no filler.

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?

There is no output schema, so the description must describe what comes back, and it does so thoroughly (today/7d/month/all-time counts, day-by-day breakdown, plan-month delivery split by campaigns/AI answers/flows, clicks and click rate, reach, top keywords, per-account auth state). An agent has everything needed to decide and call correctly.

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 description coverage is 100% and the single instagramAccountId parameter is fully documented in the schema, including where to obtain the id. The description adds nothing about the parameter, 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 resource and scope ('headline numbers for the whole workspace') and enumerates the exact metrics returned, from DMs sent today/7d/month/all-time through link clicks, reach and top keywords. An agent can distinguish it from per-account tools like instagram_post_stats or account_usage without opening any schema.

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?

Gives concrete trigger phrases ('how did I do this week', 'is anything working', 'which keyword gets the most DMs') and an explicit anti-pattern ('ask once and reuse the answer rather than calling it per question'). It does not name sibling tools it should be preferred over, so it stops short of full alternative routing.

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